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

<passage>:
thought it might be. How long since you had your last rejuvenation? And who gave it?” something inside him had been forcing him to make this decision. feel it. Some of the panic symptoms were returning the pulse in his neck was pounding and his breath was growing difficult. Sweat ran down his sides from And maybe it would do no good. the doctor studied it. “My sixteenth.” It wasn’t going right. He could lot of people couldn’t rejuvenate cure any allergy or asthma. had sworn the shot would serious, but quite definite—as well as other signs of aging. I’m afraid the treatment didn’t take fully. It might have been some unconscious block the coffee stronger than usual and it seemed to cut through some of the thickness in his head. “I guess I’m getting old, Amanda.” She smiled dutifully at the time-worn joke, but he knew she “Just a little tired,” he told give you another treatment. Any her, refilling the cup. She’d made reason you can’t begin immediately?” was more important. It hadn’t been a joke about his growing old, after all. But now, in a few days, he’d be his old—no, of course not—his young self again! Even his hair had seemed thinner, though that, of course, was impossible. He resented every second of it. It was as if the almost forgotten specter of age stood beside him, SHE JERKED her gaze away guiltily and turned to the incoming basket. “Mostly drugs for where the clamps were adjusted about his head and the earpieces were fitted. The drugs were shot painlessly into his arm and the light-pulser was adjusted to his brain-wave pattern. It had been nothing like this his first time. Then it had required months of mental training, followed by crude mechanical and drug hypnosis for other months. Somewhere in every human brain lay the memory of what his cells “I’m all right!” he told her sharply. Then he steadied himself themselves, with the brain as only a linkage to it. They’d discovered that, and the fact that the mind could effect physical changes in the body. Even such things as cancer could be willed out of existence—provided the brain could be reached far below the conscious level and forced to within minutes, even—but finding the mechanism in the brain that worked those miracles had taken an incredible amount of study and finding a means of bringing it under control had taken even longer. Now they did it with dozens of mechanical aids in addition to the hypnotic instructions—and did it usually in a single sitting, with the full transformation of the body taking less than a week after the treatment! But with all the equipment, it shuttle. He fingered the microstrip inside while he drank another message that had come on the could relax so easily.... He came out of it without even a headache, while they were 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 find himself suddenly young 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. an injection of some kind and another sample of his blood was We’ll know by then whether you’ll need more treatment. Ten o’clock okay?” “But I’ll be all right?” The discovery that men could live practically forever had put awake most of the night again, trying to recall them. The outside line buzzed musically, recovered, he could still sense the glances of the others, as if he patience was still foreign to him. real reason. Certainly they weren’t forcing themselves on him. He remembered once when he’d had a cold, before they finally licked can send a message on the shuttle, begging for their secret in a What he needed was a good night’s sleep after a little relaxation. Even that failed him, though. He’d developed one of the finest made in two centuries on your part, some infection not were finished, and the older men were too conservative for really new thinking. There was a measure of truth in it, unfortunately. “They’ll slow up when their he’d developed through his old answers. “We’re still ahead in medicine and we’ll get the the years helped to add to the interrupting the work of making THE YOUNGER man stared at him with the strange puzzled they could only bring him back to about thirty, instead of the normal early twenties. Would that reduce the slice of eternity that rejuvenation meant? And what days. We can have the secret of Or suppose it wasn’t rejuvenation, after all this antigravity in less than a had happened to Sol? permanently? thickness pushing back at his mind and tried to fight it off. He’d suppose something were still there and the circles under his eyes. He searched for partly believing it. “Rats don’t have minds that could show any 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 could correct for errors on arrival. Maybe if we put in stronger signaling transmitters....” “Yeah. Maybe in two centuries then shuddered. It hadn’t been that kind of spring for him—not this rejuvenation nor the last, nor the one himself and partially succeeded, until he reached the doctor’s office. Then it was no longer necessary 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 Now that he knew there was reason for his fear, it seemed to slowly. The belligerence ran out numbed him. “I’d rather know the whole truth,” he said. His voice sounded of him. The rejuvenation...?” dead in his ears. “The worst first. He looked sick, for he had no vanish, leaving a coldness that Cobb sighed and yet seemed relieved. “It may take longer, but eventually we’ll find a way. With time cellular memory. It loses a little each time. And the plan for short-term benefits. Usually it was too easy to realize that, and the sight of the solid, time-enduring have given him a sense of security. Today, though, nothing seemed to help. He felt choked, imprisoned, supposed to tell you, of course. It’s going to be tough enough when they’re ready to let people consolation. We’ve got a longer time scale than we used to have—but it’s in centuries, not in Cobb spread his hands unhappily. “Thirty years, maybe. But we can make them better. Geriatric knowledge is still on record. We can fix the heart and all the rest. You’ll be in good physical condition, better than your grandfather—” “And then....” Giles couldn’t pronounce the words. He’d grown old and he’d grow older. And eventually he’d die! An immortal man had suddenly stop twice to catch his breath and fight against the pain that clawed at his chest. When he he meant it. The man had done all he could and had at least saved him the suspense of growing numbed, and began driving mechanically, no longer wondering about the dangers that might possibly and a long drink in his hand. The alcohol combined with the reaction from his panic to leave him almost himself again. After all, there was nothing to worry about Earth’s doctors could cure anything. that might even be useful. morose man the last few times he’d seen him, but that could hardly explain his taking a twenty-year In the future, men would It would be cold comfort but it was something. And he might “As all right as I’ll ever be,” he told her. “They tell me I’m just growing old.” This time her laugh was heartier. He caught himself before he years of practice. Giles felt better, realizing it wouldn’t be one of the younger men. been delivered by some doctor? It didn’t matter, but it would explain things, at least. needles and the machinery behind the doctor began working on it. age? Let’s see it.” He inspected it and began making tests. Some were older than Giles could remember—knee reflex, blood pressure, pulse

<question>:
How does rejuvenation work?

<options>:
A it re-trains the brain to develop younger cells
B it injects a serum in the body that reverses time
C exercises are done to re-energize muscles
D drugs convince the body to feel younger

<answer>:

A