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

<passage>:
Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] Pioneers have always resented their wanderlust, hated their hardships. But the future brings a new grudge—when new air units now. There was a time when we had to be very careful about things like smoking." The very young man was annoyed. A nod confirmed this. It was the older man's turn to look thoughtful. "You know, I'm sure, is worth it." "I suppose so, but—" and canned air until your insides felt as though they were plated with tin. Life in a cramped, smelly little hut where you could take only ten steps in any one direction. Their little scientific home of 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. He tapped out his reply: " No! " There was a silence and then the key stammered once more in a sudden fit of bureaucratic rage. Chapman stuffed a rag under it and ignored it. He turned to the hammocks, strung against the bulkhead on the other side of the room. The chattering of the key hadn't awakened anybody they were still asleep, making the animal noises that people usually make in slumber. 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 face, looked as if he had just squirmed under the tent to his personal idea of heaven. Donley and Bening were lying perfectly still, their covers not mussed, sleeping very lightly. whispered back. "What did you say?" He shrugged. "No." "You kept it short," somebody else whispered. It was Donley, up and sitting on the side of his hammock. "If it had been me, I would have told them just what they could do about it." "Kind of. Who wouldn't be?" "Well, don't let it throw you. They've never been here on the Moon. They don't know what it's like. All they're trying to do is get a good man to stay on the job a while longer." " All they're trying to do," Chapman said sarcastically. "They've got a fat chance." "They think you've found a home here," Donley said. That's what happened to guys like Dixon, Chapman thought. On the Moon, 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 you're going to do once you get back?" It hit them, then. Dowden and Bening looked blank for a minute and "I don't know," Chapman said slowly. "I guess I was trying not to think of that. I suppose none of us have. We've been like little kids who have, but I think I know what you mean." He warmed up to it as the idea sank in. "Just what the hell are you going to do?" "Nothing very spectacular," Chapman said, smiling. "I'm going to rent Then I think I'll see somebody." "Who's the somebody?" Donley asked. to the expedition. Then I think I'll go home and see my wife." They were quiet. "I thought all members of the groups were supposed to be single," Donley said. "They are. And I can see their reasons for it. But who could pass up thought. They were going to go home in a little while and the idea was just starting to sink in. "You know, Chap," Donley said, "it won't seem like the same old Moon before they left. Donley was right after them. There was an outcropping of rock that he wanted a sample of and some strata he wished to investigate. and that we stay healthy and happy. I think you'd blow our noses for us if we caught cold. But some day, Chap old man, you're gonna find out that your little boys can watch out for themselves!" asked. "Oh, I know what we said a little while ago, but I mean seriously." He studied his hands. "I think what I miss most is people—all kinds of people. Bad people and good people and fat people and thin people, and people I can't understand. People who wouldn't know an atom from an artichoke. And people who wouldn't give a damn. We're a quarter of a million miles from nowhere, Julius, and to make it literary, I think I "Yes." "You're not like Dahl. You've never mentioned it." "Same reason you didn't mention your wife. You get to thinking about it." he was interested in. He forgot to check for leaks and whether or not the valve on his tank was all the way closed. We couldn't get to him in time." 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 themselves. The Moon's a new environment and you have to learn how to it's somebody else's turn now. He volunteered for it. I think I was fair in explaining all about the job when you talked it over among yourselves." much of a kid. He volunteered because he thought it made him look like a hero. He doesn't have the judgment that an older man would have. That you have." His voice trailed away. "It's just that I think it's such a damn important job." Klein had gone out in a last search for rock lichens and Chapman date. His signature was right beneath Dixon's. He frowned when he thought of Dixon and slid back the catch on the top of the bag and locked it. They should never have sent a kid like Dixon to the Moon. He had just locked the bag when he heard the rumble of the airlock and the soft hiss of air. Somebody had come back earlier than expected. He watched the inner door swing open and the spacesuited figure clump in sweat and his eyes were frightened. He moistened his lips slightly. "Do—do you think they'll ever have mean, considering the advance of—" "No," Chapman interrupted bluntly. "I don't. Not at least for ten home tomorrow. I kept thinking, hoping, that maybe somehow—" He was fumbling it badly, Chapman thought. But I couldn't ask any of the others you were the only one who could, the only one who was qualified!" all he knew about him. Dahl, Robert. Good mathematician. Graduate from one of the Ivy League schools. Father was a manufacturer of stoves or something. It still didn't add, not quite. "You know I don't like it here any more evaporating. "If you have any report to make, I think you had better get at it," the bunker, taking off their suits. The newcomers were impressed and solemn, very much aware of the tremendous responsibility that rested on their shoulders. Like Donley and Klein and the members of the Second Donley and the others were all over them. How was it back on Earth? Who had won the series? Was so-and-so still teaching at the university? What was the international situation? Some of the men in the Third had their luggage with them. One of them—a husky, red-faced kid named Williams—was opening a box about a foot square and six inches deep. Chapman watched him curiously. smuggle something like that up to the Moon instead of his phonograph. "Well, look, Mr. Chapman, is there any place where we can talk together privately?" They walked over to one corner of the bunker. "This is about as private "I hadn't heard of them." "Oh, yes, big plans . They're working on unmanned, open-side rockets now that could carry cargo and sheet steel for more bunkers like this. The captain vaguely felt the approach was all wrong. "Is that all?" consider anything else you had in mind, if it was more money or...." "The answer is no," Chapman said. "I'm not interested in more money the project or impending changes, perhaps you'd better tell him before you go."

<question>:
What nations do the astronauts on the moon represent?

<options>:
A United Kingdom
B United States
C United States, Russia
D Unknown

<answer>:

D