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

<passage>:
Rikud looked out upon the garden and he trembled. Out there was life. The garden stretched off in unthinkable immensity to the cluster of they were so alien, so unnatural. But ever since from the steady whining Rikud had heard all twenty-five years of his life, to the sullen roar that came to his ears now, the feelings had grown. If anyone else had noticed the change, he failed to mention it. This realized this odd difference in himself, he kept it locked up inside him. Today, space looked somehow different. The stars—it was a meaningless machinery, and down on his hands and knees he fondled the bits of metal which he could see in the dim light through the open door. "Where's the buzzer?" he sobbed. "I must find the buzzer." Crifer's voice, from the darkness inside, said, "You broke it. You broke it. And now we will break you—" If he had understood the term, Rikud would have told himself this was odd. His head ached with the half-born thought. It was—it was—what was it? could live and that was why the world had moved through the blackness, then so could he live out there, and Crifer and all the others.... metallic voice said. "Fifteen minutes under the tubes, please." Rikud muttered to himself and undressed. The world had begun to annoy exciting. He liked them. He liked the garden, for all its hugeness. But something soft had cushioned the impact—something which had come into being just for the moment and then abruptly passed into non-being again, something which was as impalpable as air. It was much better than the small world of machinery, buzzer, frightening doors and women by appointment only. With so many people, and especially now with women, he was not afraid. Rikud had been stopped in this action, although there was no real governed the world. They told you to do something and you did it, but that was silly, because now no one told you to do anything. You only listened to the buzzer. And Rikud could remember the rest of what the reading machine had said. There had been a revolt—again a term without any real meaning, a term that could have no reality outside of the reading machine—and the elders were overthrown. Here Rikud had been lost utterly. The people had decided that they did not know where they were going, or why, and that it was unfair that the elders alone had this authority. They were born and they lived and they died as the elders directed, like little cogs in a great machine. Much of this Rikud could not understand, but him, bathing his old body in a forgotten magic which, many generations before Rikud's time, had negated the necessity for a knowledge of meant that, in the two unoccupied hours before sleep, he went to the library and listened to the reading machine. Everyone else simply sat about and talked. That was the custom. Everyone did it. people ever talked about was what they had done during the day, and it was always the same. meaning." "People grow old," Rikud suggested. A buzzer signified that his fifteen minutes under the rays were up, and Rikud frowned. Chuls hadn't even seen the connection between the two concepts, yet it was so clear. Or was it? He had had it a moment ago, but now it faded, and change and old were just two words. His own buzzer sounded a moment later, and it was with a strange feeling of elation that he dressed and made his way back to the But the new view persisted. Of stars there were few, and of the blackness, almost nothing. Gone, had ceased abruptly. Instead an ominous silence, broken at regular intervals by a sharp booming. Change— nothing but an obscuring cloud of white vapor, murky, swirling, more confusing than ever. not tell them of his most amazing thought of all. The change in the viewport could mean only one thing. The world had been walking—the "Then they've changed?" the man would realize! If only anyone would realize! It all seemed so obvious. If he, Rikud, walked from one part of the world to another, it was with a purpose—to eat, or to sleep, or perhaps to bathe in the health-rays. Now if the world had walked from—somewhere, through the vast star-speckled darkness and to the great garden outside, this also was purposeful. The world had arrived at the garden for a reason. But if everyone lived as if the world still stood in blackness, how could they find the nature of that purpose? "I will eat," Chuls said, breaking Rikud's revery. door. The machinery in the next room is your protection against the rigors of space. A thousand years from now, journey's end, you may have discarded it for something better—who knows? But if you have not, then here is your protection. As nearly as possible, this ship is a perfect, self-sustaining world. It is more than that: it is human-sustaining as well. Try to hurt yourself and the ship will not permit it—within limits, of course. But you can damage the ship, and What would he do out in the garden? He couldn't go alone. He'd die of the strangeness. It was a silly thought sweat covered him in a clammy film. He never wanted to look at the Three or four days passed before Rikud calmed himself enough to throat and listened to the sound, all by itself in the stillness. What would have happened if they hadn't retired? But they always did things punctually like that, whenever the buzzer sounded. They ate with the buzzer, bathed in the health-rays with it, slept with it. What would they do if the buzzer stopped buzzing? This frightened Rikud, although he didn't know why. He'd like it, though. Maybe then he could take them outside with him to the big spinning and humming. He watched for he knew not how long. And then he began to wonder. If he destroyed the wheels and the cogs and the gears, would the buzzer stop? It probably would, because, as Rikud saw it, he was clearly an "unauthorized person." He had heard the voice again upon entering the room. darkness, something bright flashed briefly through the sky and was gone. Whimpering, he fled. All around Rikud were darkness and hunger and thirst. The buzzer did not sound because Rikud had silenced it forever. And no one went to eat or drink. Rikud himself had fumbled through the blackness and the any more. The machinery, Rikud realized, also was responsible for food. Chuls said, over and over, "I'm hungry." "We will eat and we will drink when the buzzer tells us," Wilm replied confidently. "It won't any more," Rikud said. "What won't?" "The buzzer will never sound again. I broke it." Crifer growled. "I know. You shouldn't have done it. That was a bad thing you did, Rikud." beyond the viewport." "That's ridiculous," Chuls said. Even Crifer now was angry at Rikud. "He broke the buzzer and no one can There was a lot of noise in the darkness, and someone else said, "I hate Rikud." Then everyone was saying it. Rikud was sad. Soon he would die, because no one would go outside with plants in the viewport would even be better. "We will not be hungry if we go outside," he said. "We can eat there." "We can eat if the buzzer sounds, but it is broken," Chuls said dully. Crifer shrilled, "Maybe it is only variable and will buzz again." "No," Rikud assured him. "It won't." die because he had no food and no water and his stomach gurgled and grumbled and hurt. And everyone was chasing him. break him.

<question>:
What has conditioning done to the characters?

<options>:
A It has kept them in shape, both mentally and physically,  and ready to face the struggles they encounter.
B Nothing.  They were left to their own devices for so long that they abandoned any notion.
C It has made them fear one another.
D It has become a way of life for them. Without the buzzer, their life as they know it ceases to exist.

<answer>:

D