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 very young man was annoyed. "I don't think I want to go," he blurted. "I don't think I would care to spend two years there." The older man blew a smoke ring and watched it drift toward the air exhaust vent. that psychologists and research men agree that research stations should be staffed by couples. That is, of course, as soon as it's practical." "But that might be a long time!" the very young man protested. "It might be—but sometimes it's sooner than you think. And the goal is worth it." "I suppose so, but—" to himself. Chapman stared at the radio key. Three years on the Moon and they didn't want him to come back. Three years on the Moon and they thought he'd be glad to stay for more. Just raise his salary or give him a bonus, the every-man-has-his-price idea. They probably thought he liked it there. you couldn't take a shower, couldn't brush your teeth, and your kidneys didn't work right. And for double his salary they thought he'd be glad to stay for another year and a half. Or maybe three. He should probably be glad he had the opportunity. The key started to stutter again, demanding an answer. Dowden, half in the bottom hammock and half on the floor, was snoring peacefully. Dahl, the poor kid who was due for stopover, was mumbling The others were awake now, with the exception of Dahl who had his face "Well, don't let it throw you. They've never been here on the Moon. man to stay on the job a while longer." " All "Why the hell don't you guys shut up until morning?" Dahl was awake, Klein jerked his thumb toward Dahl's bunk, held a finger to his lips, day of work on the Moon. In a few hours they'd be relieved by members of the Third research group and they'd be on their way back to Earth. And that includes me, Chapman thought. I'm going home. I'm finally about the grave. It had been more than eighteen months ago, but there That's what happened to guys like Dixon, Chapman thought. On the Moon, Dahl was still sitting on his hammock, trying to ignore them. left there twelve hours ago. They should get here"—he looked at his watch—"in about six and a half hours." "Chap, you know, I've been thinking," Donley said quietly. "You've been here just twice as long as the rest of us. What's the first thing you're going to do once you get back?" It hit them, then. Dowden and Bening looked blank for a minute and looked grave. Even Dahl glanced up expectantly. of that. I suppose none of us have. We've been like little kids who have waited so long for Christmas that they just can't believe it when it's finally Christmas Eve." Klein nodded in agreement. "I haven't been here three years like you have, but I think I know what you mean." He warmed up to it as the idea sank in. "Just what the hell be single," Donley said. "They are. And I can see their reasons for it. But who could pass up when he had landed with the First group. The record was old and the Donley looked sour. "I've gone out at least five hundred times," he said, "and you check me each time." "And I'd check you five hundred more," Chapman said. "It takes only through one of those and that's it, brother." Donley sighed. "Chap, you watch us like an old mother hen. You see we check our suits, you settle our arguments, you see that we're not bored "You're not like Dahl. You've never mentioned it." "Same reason you didn't mention your wife. You get to thinking about it." Being on the Moon was the opportunity of a lifetime. He thought so much let them take over cold. They have to know where you left off. They have to know where things are, how things work, what to watch out for. And then, because you've been here a year and a half and know the "Do you think Dahl will do as good a job as you've done here?" it's somebody else's turn now. He volunteered for it. I think I was fair in explaining all about the job "You did, but I don't think Dahl's the man for it. He's too young, too "I'm not the indispensable man," he said slowly, "and even if I was, it wouldn't make any difference to me. I'm sorry if Dahl is young. So was I. I've lost three years up here. And I don't intend to lose any more." Klein held up his hands. "Look, Chap, I didn't mean you should stay. I know how much you hate it and the time you put in up here. It's just—" week before, when he had opened his small gear locker and transferred its meager belongings to the bag. He hadn't actually needed to pack, of course. In less than twenty-four hours he'd be back on Earth where he could drown himself in toothpaste and buy more tee shirts than he could wear in a lifetime. He could inherited from—who was it? Driesbach?—of the First group. Dahl could probably use them or maybe one of the boys in the Third. But it wasn't like going home unless you packed. It was part of the ritual, like marking off the last three weeks in pencil on the gray steel of the bulkhead beside his hammock. Just a few hours ago, when he woke up, he had made the last check mark and signed his name and the to the Moon. Dahl. He had gone out to help Dowden on the Schmidt telescope. Maybe Dowden hadn't needed any help, with Bening along. Or more likely, considering the circumstances, Dahl wasn't much good at helping anybody Dahl stripped off his suit. His face was covered with light beads of sweat and his eyes were frightened. He moistened his lips slightly. "Do—do you think they'll ever have relief ships up here more often than every eighteen months, Chap? I mean, considering the advance of—" "No," Chapman interrupted bluntly. "I don't. Not at least for ten years. The fuel's too expensive and the trip's too hazardous. On freight charges alone you're worth your weight in platinum when they send you here. Even if it becomes cheaper, Bob, it won't come about sorry for Dahl. "It won't be too bad. There'll be new men up here and "Well, you see," Dahl started, "that's why I came back early. I wanted It hurt to look in Dahl's eyes. They were the eyes of a man who was Dahl looked as though he was going to be sick. Chapman tried to recall all he knew about him. Dahl, Robert. Good mathematician. Graduate from Dahl took the plunge. "Well, you see," he started eagerly, too far gone to remember such a thing as pride, "you know my father's pretty well fixed. We would make it worth your while, Chap." He was feverish. "It would mean eighteen more months, Chap, but they'd be well-paid months!" Chapman felt tired. The good feeling he had about going home was slowly evaporating. "If you have any report to make, I think you had better get at it," he cut in, keeping all the harshness he felt out of his voice. "It'll be too late after the relief ship leaves. It'll be easier to give the captain your report than try to radio it back to Earth from here." He felt sorrier for Dahl than he could ever remember having felt for anybody. Long after going home, Dahl would remember this. How was it back on Earth? Who had won the series? Was so-and-so still Chapman cut off a single blade with his fingernail and put it between Williams looked stricken and somebody said, "Oh, shut up, Dahl." Chapman jerked a thumb toward Dahl. "Ask him. He's in charge now." "Bob Dahl is staying for stopover. If there's something important about

<question>:
How long had Dahl been on the moon?

<options>:
A 1 year
B 6 months
C 1 year, 6 months
D 3 years

<answer>:

C