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

<passage>:
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 blinked in alarm at the wildly thrashing pattern on the tape. The boy was terrorized. He was literally pulsating with fear. Again the mute appeal in the boy's eyes. He groped for words, and none came. Finally he said, "If I could only take this off—" He fingered the grey plastic helmet. "You think that would make you feel better?" Lessing shook his head. "I don't think so, Tommy. You know what the monitor is for, don't you?" "It stops things from going out." "That's right. And it stops things from going in. It's an insulator. You need it badly. It would hurt you a great deal if you took it off, away from the Farm." "Full psi precautions?" asked Dorffman. "Certainly! And Jack—in this case, be sure 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 For they were floundering. When they were finally forced to recognize that this great and powerful force did indeed exist in human minds, with unimaginable potential if it could only be unlocked, they had crashing down about their ears as they stood sadly by and watched things happen which natural law said could never happen. They had never stronghold of psionic research at last. And face to face with the Master in the trembling flesh!" "And our controls are above suspicion." why really be certain that your instruments are measuring the children at all. It's not inconceivable that the children might be measuring the 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 In the main office building they donned the close-fitting psionic hard grey plastic material, with a network of wiring buried in the 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." across the field a group of swings, slides, ring bars and other playground paraphernalia was in heavy use. The place was teeming with youngsters, all shouting in a fury of busy activity. Occasionally a helmeted supervisor hurried by funds. Other children come to us—foundlings, desertees, children from broken homes, children of all ages from infancy on. Sometimes they stay until they have reached college age, or go on to jobs. As far as 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." He led them into a long, narrow room with chairs and ash trays, facing a wide grey glass wall. The room fell into darkness, and through the grey glass they could see three children, about four years old, playing in a large room. "They're perfectly insulated from us," said Lessing. "A variety of recording instruments are working. And before you ask, Dr. Melrose, engineer's attempts to determine what makes them go. We don't know what In the corner a flat screen was flickering, emitting a pale green fluorescent light. It hung from the wall by two plastic rods which penetrated into the children's room. There was no sign of a switch, nor a power source. As the children moved about, the screen flickered. Below it, a recording-tape clicked along in little spurts and starts of activity. moments. "Those three seem to work as a team, somehow. Each one, individually, had a fairly constant recordable psi potential of about seventeen on He inspected the block tower they were building, and stooped down to talk to them, his lips moving soundlessly behind the observation wall. The children laughed and jabbered, apparently intrigued by the game he 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 of place.... Then, quite casually, Lessing lifted off his monitor. The children 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." "That's what I think," said Lessing. "How do you know those children didn't make you take off your monitor?" Lessing blinked. "Why should they?" "Maybe they enjoy the crash when the blocks fall down." children's playroom. "See what you think." The boy sat stolidly in the corner of the room. He looked up as they came in, but there was no flicker of recognition or pleasure on his , Lessing thought suddenly. Something had suddenly gone 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 physical blow, the hate and fear and suspicion and cruelty buried and repressed in the adult mind, crushing suddenly into the raw receptors of the child's mind like a smothering fog—it was a fearful thing. A healthy youngster could survive it, even though the scar remained. But this youngster was sick— And yet an animal instinctively seeks its own protection . With trembling fingers Lessing reached out and opened the baffle-snap on the monitor. "Take it off, Tommy," he whispered. The boy blinked in amazement, and pulled the grey helmet from his head. Lessing felt the familiar prickly feeling run down his scalp as the boy stared at him. He could feel deep in his own mind the cold chill of terror radiating from the boy. Then, suddenly, it began to fade. A sense of warmth—peace and security and comfort—swept in as the fear faded from the boy's face. The fire engine clattered to the floor. They analyzed the tapes later, punching the data cards with greatest 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 balance of his mind. Then he made an adult contact, and we saw how he

<question>:
Why are the grey helmets necessary?

<options>:
A The helmets block external psionic forces.
B The helmets improve the reception of external psionic forces.
C The helmets are for safety, as the children are heavily medicated and at high risk for falling.
D The helmets amplify the childrens' psychic abilities.

<answer>:

A