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

<passage>:
... and it comes out here By LESTER DEL REY Illustrated by DON SIBLEY You will, you know, so why quibble about it? At least, you always have ... or do ... or will. I don't know, verbs get all mixed up. We aren't. It's just that things are a bit confused. And don't look at the person. I'm you thirty years from now, or you're me. I remember just for half an hour or so, until you get over it. After that you'll come who put atomic power in every home. You won't exactly believe it, but cut off your questions, and get you inside. I snap on a green button, prevents passage through time from affecting us. The luggage section You start to say something, but by then I'm pressing a black button, and everything outside will disappear. You look for your house, but it isn't there. There is exactly nothing there—in fact, there is no . You are completely outside of time and space, as best you can and you don't try it again. You turn to me, getting used to the idea. "So this is the fourth Then you feel silly, because you'll remember that I said you'd ask that. Well, I asked it after I was told, then I came back and told it "Not exactly," I try to explain. "Maybe it's no dimension—or it might if you're going to skip over the so-called fourth without for us to imagine it. When you spend thirty years thinking about it, as apparently, though there is a time effect back in the luggage space. carry a small time field with you, or you are catching a small increment of time from the main field. I don't know, and you won't "Where are we getting our air?" you ask. "Or why don't we lose it?" time nor space, apparently. How could the air leak out? You still feel Then the machine stops—at least, the field around us cuts off. You "I'm staying here," I tell you. "This is like the things they wear in this century, as near as I can remember it, and I should be able to I'll leave you. I like the looks of things here, so I won't be coming You nod, remembering I've told you about it. "What century is this, I'd told you that, too, but you've forgotten. "As near as I can guess, it's about 2150. He told me, just as I'm telling you, that it's an interstellar civilization." "What about the time machine?" you ask. future. Then the door opens, and the elevator says "first" back at us. that announces: passengers moving up a ramp, and the office is closed. You begin to get the hang of the spelling they use, though. Now there are people around you, but nobody pays much attention to you. Why should they? You wouldn't care if you saw a man in a leopard-skin you'd figure it was some part in a play and let it go. Well, people don't change much. "Downayer rien turn lefa the sign. Stoo bloss," he tells you. Around you, you hear some pretty normal English, but there are others using stuff as garbled as his. The educated and uneducated? I don't know. You go right until you find a big sign built into the rubbery surface You go up the steps, but you see that it seems to be closed. You guard. What's more, he speaks pretty clearly. Everyone says things in a sort of drawl, with softer vowels and slurred consonants, but it's rather pleasant. "Help you, sir? Oh, of course. You must be playing in 'Atoms and Lord, the genius of that twentieth century inventor! It's quite a hobby with me, sir. I've read everything I could get on the period. Oh—congratulations on your pronunciation. Sounds just like some of our oldest tapes." seems deserted and you wander up the stairs. There's a room on your goes through a crazy wiggle inside, stops turning out a continual row "Souvenir," it announces in a well-modulated voice. "This is a typical You put it in your pocket, gulping a little, and get back to the there is one labeled marked lot smaller than you thought. They seem to be in chronological order, and the latest one, marked , is about the size of a desk telephone. The earlier ones are larger, of course, clumsier, You study it, but it mentions casually the inventor, without giving his name. Either they don't know it, or they take it for granted that everyone does, which seems more probable. They call attention to the and full patent application. They state that it has all major refinements, operating on any fuel, and any amperage up to one thousand, its maximum power output being fifty kilowatts, limited by the current-carrying capacity of the outputs. They also mention that the operating principle is still being investigated, and that only such refinements as better alloys and the the cathogrids and we had to replace that, but otherwise it's exactly "Not particularly," you begin, and then realize bad manners might be conspicuous here. While you're searching for an answer, the guard pulls something out of his pocket and stares at it. arriving, but I'll be back in about ten minutes. He wants to examine it, either. they're all held down by the same whatchamaycallem effect. moves. There's a little sign under it, indicating you shouldn't touch it, since the gravostatic plate is being renewed. Well, you won't be able to change the time cycle by doing anything I You expect a warning bell, but nothing happens. As a matter of fact, happen to you. But of course, just as I did, you're going to miss a probably can't help it, anyhow. Pre-set, you might say. Well, you stagger down the corridor, looking out for the guard, but all down and try to scurry past, but you know you're in full view. Nothing world on your back, and still nothing happens. Ahead of you, the gate Something goes over your head and drops on the sidewalk just in front of your feet, with a sudden ringing sound. You don't wait to find out it. The stranger lifts an eyebrow and goes off at once when you nod You swallow several sets of tonsils you had removed years before, and There is no button on it. In fact, there's no door there. You start looking for other doors or corridors, but you know this is the original level. You get out—and realize you don't have a light. You'll never know what you stumbled over, but, somehow, you move back reach forward toward the green button and hesitate. There's a red one beside it and you finally decide on that. you and the next button you touch—the one on the board that hasn't been used so far—sends you off into nothingness. There is no beam of nerves settle back to normal. You notice a third set of buttons, with years"—and you begin waiting for the air to get stale. It doesn't because there is only one of you this time. Instead, everything flashes off and you're sitting in the machine in You'll figure out the cycle in more details later. You get into the It isn't hard to disassemble, but you don't learn a thing But when you put it together again, about an hour later, you notice something. in time, somehow, and is back to its original youth—minus the be anything but a democracy and a peaceful one—after some of the worst times in history for a few years. Your name eventually becomes as common as Ampere, or Faraday, or any other spelled without a capital letter. But you're thinking of the puzzle. You can't find any answer. One day you come across an old poem—something about some folks calling it evolution and others calling it God. You go out, make a few provisions for the future, and come back to climb into the time machine that's waiting in the building you had put around it. Then you'll be

<question>:
Which item doesn't get mentioned while they're in the year 2150?

<options>:
A flying vehicles
B diamond makers
C an elevator that you can't feel move
D a modified English language

<answer>:

A