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

<passage>:
incredible myth in a single generation! just above the white blanket of frozen air. I'd never seen a live young lady before, except in the old magazines—Sis is just a kid and Ma is pretty sick and miserable—and it gave me such a start that I dropped the pail. Who wouldn't, knowing everyone on Earth was dead except Pa and Ma and Sis and you? Even at that, I don't suppose I should have been surprised. We all But my mind was still crawly and uneasy as I pushed through the last blankets—Pa's got them faced with aluminum foil to hold in the heat—and came into the Nest. four of us and our things. The floor is covered with thick woolly rugs. Three of the sides are blankets, and the blankets roofing it touch Pa's head. He tells me it's inside a much bigger room, but I've the clocks are alarm and we can use them to remind us. In the early days there was only Ma to take turns with Pa—I think of that when she gets difficult—but now there's me to help, and Sis too. It's Pa who is the chief guardian of the fire, though. I always think of him that way: a tall man sitting cross-legged, frowning anxiously at the fire, his lined face golden in its light, and every so often It slowly melts and vanishes and refreshes the Nest and feeds the fire. The blankets keep it from escaping too fast. Pa'd like to seal the whole place, but he can't—building's too earthquake-twisted, and the fire go out. Next there's the nitrogen, which doesn't count one way or the other, though it's the biggest part of the blanket. On top of that and easy to get at, which is lucky for us, there's the oxygen that keeps us alive. Pa says we live better than kings ever did, breathing pure oxygen, but we're used to it and don't notice. Finally, at the All of these gases in neat separate layers. Like a pussy caffay, Pa died. "Not like anything I ever saw," I told him. He stood for a moment frowning. Then, "I'll go out with you, and you show it to me," he said. Ma raised a howl at the idea of being left alone, and Sis joined in, too, but Pa quieted them. We started climbing into our outside clothes—mine had been warming by the fire. Pa made them. They have on the roof to check if it's working all right. That's our worst trip and Pa won't let me make it alone. and the two of us go out. Pa led the way and I took hold of his belt. It's a funny thing, I'm not afraid to go by myself, but when Pa's along I always want to hold on to him. Habit, I guess, and then there's no denying that this time I was a bit scared. You see, it's this way. We know that everything is dead out there. Pa the last folks die who weren't as lucky or well-protected as us. So we out all the time. and all the rest that happened when the dark star captured the Earth. lurking out there, watching, waiting, getting ready. Inside, he said to me, touching helmets, "If you see something like that again, son, don't tell the others. Your Ma's sort of nervous these days and we owe her all the feeling of safety we can give her. Once—it was when your sister was born—I was ready to give up and die, but your week all by herself when I was sick. Nursed me and took care of the two of you, too." "You know that game we sometimes play, sitting in a square in the Nest, the Nest and took off our outside clothes, Pa laughed about it all and told them it was nothing and kidded me for having such an imagination, but his words fell flat. He didn't convince Ma and Sis any more than days, and how it all happened. He sometimes doesn't mind telling that story, and Sis and I sure like to listen to it, and he got my idea. So we were all settled around the any more than I can believe in the swarming number of them. Imagine Wanting it even, or at least wishing it were over so as to end their nervousness. As if all folks didn't have to hang together and pool every bit of warmth just to keep alive. And how can they have hoped to get involved. The Sun and the newcomer fought over the Earth for a carried us off. The Sun got a consolation prize, though. At the last minute he managed to hold on to the Moon. That was the time of the monster earthquakes and floods, twenty times worse than anything before. It was also the time of the Big Jerk, as Pa The Big Jerk didn't last long. It was over as soon as the Earth were scared or brave or crazy or stunned, or all four, but he's sort of leery of the subject, and he was again tonight. He says he was mostly too busy to notice. rotation had been slowed in the tug-of-war, so that the nights were ten others clustered around the furnaces in the basements where we go for coal. In one of the rooms, an old man sits stiff in a chair, with an arm and a leg in splints. In another, a man and woman are huddled together in sitting with a pile of wraps huddled around her, looking hopefully toward the door, as if waiting for someone who never came back with warmth and food. They're all still and stiff as statues, of course, but a little light. They scared me pretty bad and made my heart pound, especially the young lady. Now, with Pa telling his story for the umpteenth time to take our minds the use of dragging it out for a few years? Why prolong a doomed existence of hard work and cold and loneliness? The human race is done. The Earth is done. Why not give up, I asked myself—and all of a sudden Pa was saying. "The earth's always been a lonely place, millions of miles from the next planet. And no matter how long the human race might heard the steps, too, and was talking loud so we maybe wouldn't hear them, "right then and there I told myself that I was going on as if we had all eternity ahead of us. I'd have children and teach them all Well, my heart couldn't have been stopped for more than four or five They were simply people, you see. We hadn't been the only ones to survive we'd just thought so, for natural enough reasons. These three people had survived, and quite a few others with them. And when we found out how they'd survived, Pa let out the biggest whoop of joy. for bombs, they had enough to go on for thousands of years. They had broke down and cried. They'd been scouting around for survivors, but they never expected to now I was just embarrassed and scared of her, even though she tried to be nice as anything to me. I sort of wished they'd all quit crowding the Nest and let us be alone and get our feelings straightened out. "It's different, now that we know others are alive," he explains to me. "Your mother doesn't feel so hopeless any more. Neither do I, for that matter, not having to carry the whole responsibility for keeping the human race going, so to speak. It scares a person." boiling away and Ma and Sis sleeping in the warmth and the flickering light. "It's not going to be easy to leave the Nest," I said, wanting to cry, kind of. "It's so small and there's just the four of us. I get scared at the idea of big places and a lot of strangers." He nodded and put another piece of coal on the fire. Then he looked at the little pile and grinned suddenly and put a couple of handfuls on, just as if it was one of our birthdays or Christmas. "You'll quickly get over that feeling son," he said. "The trouble with till I grow up? I'll be twenty in only ten years.

<question>:
How many people are left alive on Earth?

<options>:
A a number of people in various places
B Only the boy
C Only the boy, his family, and some people in New Mexico
D Only the boy, his mom, his dad, and his sister

<answer>:

A