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

<passage>:
eternal night and turning history into incredible myth in a single generation! 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 huddles back against the blankets hanging around the Nest. Pa says it of the cruel little stars had come down out of the airless sky to investigate why the Earth had gone away from the Sun, and maybe to hunt down something to torment or terrify, now that the Earth didn't have of one of the windows to get me. Then I had the wit to go back inside. Pretty soon I was feeling my familiar way through the thirty or so blankets and rugs Pa has got hung around to slow down the escape of air from the Nest, and I wasn't quite so scared. I began to hear the tick-ticking of the clocks in the Nest and knew I was getting back 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. Let me tell you about the Nest. It's low and snug, just room for the 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 and without a sun or moon, that would be easy to do. The fourth wall has blankets all over except around the fireplace, in which there is a fire that must never go out. It keeps us from freezing old days—vestal virgins, he calls them—although there was unfrozen air all around then and you didn't really need one. It slowly melts and vanishes and refreshes the Nest and feeds the the first blankets, along with extra coal and cans of food and other things, such as pails of snow to melt for water. We have to go way down water, you have to make sure you don't go too high and get any of that stuff mixed in, for it would put you to sleep, maybe for good, and make 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 the entry-slit in the blankets and wringing her hands together—the hand where she'd lost three fingers from frostbite inside the good one, as usual. I could tell that Pa was annoyed at me scaring her and wanted to explain it all away quickly, yet could see I wasn't fooling. "Long enough for it to pass five windows and go to the next floor." comes crawling toward the Nest, just like an animal snuffing for 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 Nest. It's been watching us all this time, and now it's coming after knocks off the ice that keeps trying to clog it. Once a week he goes up 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. out all the time. quite a while after filling his pail, and just as we were going inside 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 Mother kept me trying. Another time she kept the fire going a whole "You know that game we sometimes play, sitting in a square in the Nest, it only so long, and then he's got to toss it to someone else. When the Nest and took off our outside clothes, Pa laughed about it all and minute he managed to hold on to the Moon. That was the time of the monster earthquakes and floods, twenty times broke or skulls cracked. We've often asked Pa how people acted during that time, whether they 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. then and in the Big Jerk. So he had to start over and throw the Nest together quick without any advantages, just using any stuff he could lay his hands on. I guess he's telling pretty much the truth when he says he didn't have any time to keep an eye on how other folks behaved, either then or in the Big Freeze that followed—followed very quick, you know, both because the dark star was pulling us away very fast and because Earth's 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. 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 just like life. Pa showed them to me once in quick winks of his flashlight, when Now, with Pa telling his story for the umpteenth time to take our minds dark star to get us. Or maybe, I thought, both ideas might be true. Something coming down Nest. Pa was telling about the early years in the Nest and had come to the pictures of those, but I can't describe how they feel—or the fire's glow. It makes everything else worth while. And that's as true for the last man as the first." And still the steps kept shuffling closer. It seemed to me that the inmost blanket trembled and bulged a little. Just as if they were 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 enlarge and seal the Nest. I'd do what I could to keep everything bright and unwinking in her hand. And two other faces peered over her shoulders—men's faces, white and staring. 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 us. One of the men kept saying, "But it's impossible, I tell you. You . So after they'd got things going smoothly at Los Alamos, which had taken years, they'd finding us. Their instruments had given them a wrong steer and they'd wasted some time in the building across the street. By now, all five adults were talking like sixty. Pa was demonstrating to the men how he worked the fire and got rid of the ice in the chimney that they found the Nest a bit smelly, but they never mentioned that at I sort of wished they'd all quit crowding the Nest and let us be alone And when the newcomers began to talk about our all going to Los Alamos, as if that were taken for granted, I could see that something of the fire go out." Well, the strangers are gone, but they're coming back. It hasn't been decided yet just what will happen. Maybe the Nest will be kept up as hankering to see them for myself. You ask me, Pa wants to see them, too. He's been getting pretty 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 with just the Nest. Now it'll be good to have a real huge world again, the way it was in the beginning." I guess he's right. You think the beautiful young lady will wait for me till I grow up? I'll be twenty in only ten years.

<question>:
How many times did the son leave the Nest in the story?

<options>:
A Four
B Two
C One
D Three

<answer>:

B