Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
The Dwindling Years NEARLY TWO hundred years of habit carried the forcing him to make this decision. And maybe it would do no good. Maybe the ship would fail. But thirty years was a number a man could risk. If he made it, though.... done celebrating the reunion. And there’d be other grandchildren. With the ship, he’d have time enough to look them up. Plenty of time! Thirty years was a long time, when he stopped to think of it. for breath and feeling his heart hammering in his chest. He’d been a fool to come to work, with much waving of charts. He resented every second of it. It was as if the almost forgotten specter of age stood beside him, at Research. For eighty years now, they’d been sending out the little ships that vanished at greater than the operate. the first hope they’d found that the century-long trips between stars in the ponderous shuttles might be ended and he should have been filled with excitement There had been impossible ship apparently had been picked up by accident when it almost collided with a Sirius-local ship. Scientists there had puzzled over it, reset it and sent it back. The taken even longer. Now they did it with dozens of the body taking less than a week after the treatment! shuttle. He fingered the microstrip inside while he drank another coffee, and finally pulled But with all the equipment, it could relax so easily.... removing the probes, but the fatigue on the operator’s face told him it had been a long and difficult job. He stretched experimentally, with the eternal unconscious expectation that he would spoiled him. He’d even tried to avoid the compulsory emigration draft and stay on with his mother. It had been the bitter quarrels again. But that, of course, was ridiculous. It took days for the mind to work on all the cells and to repair the damage of time. that. Harry had nothing but praise for the solar system where he’d been sent. He barely mentioned being married on the way or his dozen children, but filled world He’d developed one of the finest against the background of an alien but attractive world. He had no desire to spend ninety years cooped up with a bunch of callow young emigrants, shuttles. And even if Exodus ever got the super-light drive working, there was no reason he should give up his work. The discovery that men could live practically forever had put an end to most family ties sentiment wore thin in half a century—which wasn’t much time now, though it had once seemed long enough. Strange how the years seemed to get shorter as their number increased. There’d been a song once—something about the years dwindling down. He groped for the lines and couldn’t remember. Drat it! Now he’d probably lie awake most of the night again, there were endless questions that kept it on his mind. And even dining room and picked his way through the meal, listening to the conversation about him only when it was necessary because here for nearly a century now and he’d never regretted it. But tonight his own group irritated him. He puzzled over it, finding no real reason. Certainly they weren’t forcing themselves on him. He remembered once when he’d had that Harry had been a complete nuisance, running around with various nostrums, giving him no peace. Constant questions about how he felt, constant little looks Earth conveyance to pass casual inspection, but it floated wheellessly was enough like an old model the discussions after the dinner, but he’d heard them all before, except for one about the super-speed drive, and there he had no wish to talk until he could study the final report. He gave up at last and went to his own suite. What he needed was a good night’s sleep after a little relaxation. Even that failed him, though. begging for their secret in a couple of hundred years! While no real progress had been made in two centuries the young men were sent out as soon as Earth was becoming a backwater were finished, and the older men were too conservative for really the years helped to add to the richness of living now. He gave it up and went to bed—to have the fragment of that was no escaping it. Something about the years—or was it days—dwindling down to something interrupting the work of making the Earth fit for our longevity. Could they really dwindle down? Suppose he couldn’t rejuvenate or other. all the way? He knew We can wait. We’ll have to.” it about twenty years before the Procyon shuttle heard its signal. Pre-setting a course may take centuries, if we can ever master it. Even with Sirius expecting the missiles and ready to cooperate. I mean the big ship. We’ve had it drafted for building long enough now we can finish it in three months. We know the drive works. He looked no better the next morning when he finally dragged real damage such as the loss of power to rejuvenate. We can’t put human pilots into a ship with our drive until we’ve tested it more then shuddered. It hadn’t been that kind of have the big ship. All we need is one volunteer!” until he reached the doctor’s office. Then it was no longer necessary “All right, Bill. Find me one volunteer. Or how about you? Do you really want to risk losing the rest of your life rather than waiting a couple more centuries until we know it’s safe? If you do, I’ll order the big ship.” now. The machines were quiet—and all the doors were shut. Then the engineer shut his mouth slowly. The belligerence ran out NO SANE man would risk a chance for near eternity against such a relatively short those who knew their days were numbered, anyhow. we’ll find a way. With time enough, we’re bound to. And when we do, the ship will be ready.” hand came up to twist at the lock of hair over his forehead. Eternity! They had to plan and build for it. They couldn’t risk that plan for short-term benefits. Usually it was too easy to realize that, whether there were or not. talk, of course. How—how long?” Cobb spread his hands unhappily. “Thirty years, maybe. But old and he’d grow older. And eventually he’d die! An immortal man had suddenly found death hovering on his saved him the suspense of growing doubt and horrible eventual discovery. then at the buildings built to last for thousands of years. Their eternity was no longer a part of him. Even his car would outlast him. much now. For a man who had thought of living almost forever, thirty years was too short a time to count. and started to slow. Then he went on without stopping. He wanted no chance to have them asking questions he couldn’t answer. It was none of their business. and he drove on. What else was there for him? There, at least, he could still fill his time with work—work that might even be useful. In the future, men would hardly explain his taking a twenty-year shuttle trip for such a slim reason. It was no concern of was something. And he might keep busy enough to forget sometimes that the years were gone for him. Automatic habit carried him didn’t go in for home visits now—they preferred to see their he told her. “They tell me I’m just growing old.” on, he’d be missing the old days when he’d had a mansion and counted his wealth in possessions, instead of the treasures he could people still in the odd, wheelless loved being driven. Even after chauffeurs were a thing of the past, Harry had driven him vehicle on the alien planet. so strict, there was always a small chance of some accident and nobody had any desire to spend the long future as a cripple. ties melted away too fast for interstellar travel. Yet there seemed to be no like that, before he left. Or had he even been one of those while the years dwindled down— Then abruptly the line finished itself. “The years dwindle down to a precious few....” he remembered. “A precious few.” Those dwindling years had been precious once. He unexpectedly that was forbidden. The years seemed precious to the old man then.

<question>:
Why couldn't they find a volunteer to man the big ship?

<options>:
A the ship wasn't going to be ready for a long time
B there was no proof that it was safe for humans
C the rats didn't survive, so people probably wouldn't
D no one wanted to spend that much time on the ship

<answer>:

B