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

<passage>:
"But the book is due! The Conference speech—" be laughed at? Do you think we could stand a little discredit, making silly asses of ourselves? Because when I finish this book, we'll be laughed out of existence. There won't be any Authority in psionics for a while—and maybe that way one of the lads who's really "He's gone completely hay-wire. Nobody's been able to get near him "Why?" "No. Oh, no!" "It stops things from going out." "That's right. And it stops things from going in. It's an insulator. ran a hand through sparse grey hair. "See what you can do for the boy downstairs." "Full psi precautions?" asked Dorffman. "Certainly! And Jack—in this case, be sure get back to work again. The other letter cheered him a bit more. It bore the letterhead of the International Psionics Conference: Dear Dr. Lessing: In recognition of your position as an authority on human Psionic behavior patterns, we would be gratified to schedule you as principle earlier papers had only hinted at the direction he was going—but the book would clear away the fog. He scanned the title page proudly. "A Theory of Psionic Influence on Infant and Child Development." A good title—concise, commanding, yet modest. They would read it, all right. And they would find it a light shining brightly in the darkness, a that this great and powerful force did indeed exist in human minds, with unimaginable potential if it could only be unlocked, they had plunged eagerly into the search, and found themselves in a maddening crashing down about their ears as they stood sadly by and watched the office in awe. "I'm really overwhelmed," he said after a moment. "Within the stronghold of psionic research at last. And face to face with the Master in the trembling flesh!" Connecticut and see for myself how much pressure these experimental controls you keep talking about will actually bear. But mostly, I want to see just what in psionic hell you're so busy making yourself an misdirected, is all." "According to your Theory, that is." "Wildly unorthodox approach to psionics—but at least you're energetic ." "Oh, yes. We certainly were." "Yet you said that you didn't know what." "That's right," said Lessing. "We don't." "And you don't know why "Yes, wasn't it," mused Melrose, scratching his bony jaw. "Only took them seventy years to climb it, thanks to a certain man's theories. I wonder how long it'll take psionics to crawl out of the pit you're digging for it?" "We're not digging any pit," Lessing exploded angrily. "We're exploring—nothing more. A phenomenon exists. We've known that, one way or another, for centuries. The fact that it doesn't seem to be bound by it isn't governed by natural law. But how can we define the law? How can we define the limits of the phenomenon, for that matter? We can't work in the dark forever—we've got to have a working hypothesis to "For a working hypothesis—yes. We've known for a long time that every human being has extrasensory potential to one degree or another. Not that, of course, but I'll play along." Lessing glared at him. "When we began studying this psi-potential, we found out some curious things. For one thing, it seemed to be immensely more powerful and active in infants and children than in adults. Somewhere along the line as a child grows up, something happens. We don't know what. We do know that the child's psi-potential gradually withdraws deeper and deeper into his mind, burying itself farther and farther out of reach, just the way a tadpole's tail is absorbed deeper underground? What buries it so deeply that adult human beings can't get at it any more?" "And you think you have an answer," said Melrose. "We think we might be near an answer. We have a theory that explains the available data." The shuttle car bounced sharply as it left the highway automatics. long, low building. "All right, young man—come along," said Lessing. "I think we can show you our answer." In the main office building they donned the close-fitting psionic monitors required of all personnel at the Farm. They were of a substance, connected to a simple pocket-sized power source. "The major problem," Lessing said, "has been to shield the children from any external psionic stimuli, except those we wished to expose them to. Our goal is a perfectly controlled psi environment. The monitors are quite effective—a simple Renwick scrambler screen." "It blocks off all types of psi activity?" asked Melrose. "As far as we can measure, yes." "Which may not be very far." psionics research is concerned, we are not trying to be teachers. We are strictly observers. We try to place the youngsters in positions where they can develope what potential they have— without the presence of external psionic influences they would normally be subject to. The results have been remarkable." they are all empirical instruments, and they would all defy any engineer's attempts to determine what makes them go. We don't know what makes them go, and we don't care—they go. That's all we need. Like moments. "Those three seem to work as a team, somehow. Each one, individually, had a fairly constant recordable psi potential of about seventeen on the arbitrary scale we find useful here. Any two of them scale in at thirty-four to thirty-six. Put the three together and they operate He inspected the block tower they were building, and stooped down to the tower with his thumb. The tower quivered, and the screen blazed out with green light, but the tower stood. Carefully Lessing jogged all the foundation blocks out of place until the tower hung in midair, clearly unsupported. The children watched it closely, and the foundation blocks inched still further out continued staring at the tower as the screen gave three or four violent The block tower fell with a crash. to see what I'm driving at," he said slowly. "Yes," said Melrose. "I think I'm beginning to see." He scratched his jaw. "You think that it's adult psi-contact that drives the child's potential underground—that somehow adult contact acts like a damper, a sort of colossal candle-snuffer." "Maybe they enjoy the crash when the blocks fall down." "But that wouldn't make any difference, would it? The blocks still fall down." "And you'd express that opinion in a professional meeting?" "I would." "And as an Authority on psionic behavior patterns," said Melrose cut it off under him. Well, that's his worry, not yours." Dorffman's "He wasn't objecting to the theory. He's afraid of what happens after the theory." "So it seems. But why?" horribly wrong—could the boy really be sensing the source of the trouble? Lessing felt a cold knot gather in the pit of his stomach. He knew what happened when adult psi-contact struck a psi-high youngster's mind. He had seen it a hundred times at the Farm. But even more—he had felt it in his own mind, bursting from the child. Like a violent The fire engine clattered to the floor. Dorffman stared at it angrily. "It's obviously wrong," he grated. "It before. There must be an error." "Of course," said Lessing. "According to the theory. The theory says that adult psi-contact is deadly to the growing child. It smothers their potential through repeated contact until it dries up completely. We've proved that, haven't we? Time after time. Everything goes according to the theory—except Tommy. But Tommy's psi-potential was drying up there on the Farm, until the distortion was threatening the They sat silently for a while. Then Dorffman said: "What are you going

<question>:
Why does the block tower fall down?

<options>:
A Lessing removed his helmet.
B The children used their psi powers to influence Lessing into removing his helmet.
C The children removed their helmets.
D Unknown. It is too early in the field of psi research to accurately determine the answer.

<answer>:

D