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

<passage>:
The Sense of Wonder The garden stretched off in unthinkable immensity to the cluster of Extensive research did not uncover any evidence that . This was why the world had moved should across the darkness and the stars for all Rikud's lifetime and more. the great changeless sweep of space. He could not quite explain the from the steady whining Rikud had heard all twenty-five years of his realized this odd difference in himself, he kept it locked up inside him. Today, space looked somehow different. The stars—it was a meaningless pinpoints of light on the black backdrop in the viewport—were not apparent in the speckled profusion Rikud had always known. Instead, "Where's the buzzer?" he sobbed. "I must find the buzzer." by itself in the middle of the viewport. 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 could live and that was why the world had moved through the blackness, Chuls' reminder fostered uneasiness. Often Rikud had dreamed of the time he would be thirty and a father. Whom would the Calculator select as his mate? The first time this idea had occurred to him, Rikud ignored it. But it came again, and each time it left him with a feeling he could not explain. Why should he think thoughts that no other man had? Why should he think he was thinking such thoughts, when it always embroiled him in a hopeless, infinite confusion that left him with a He stared out into the garden, and off into the distance, where the headache? explain had entered the elder man's head for a moment, but it had water to drink. was a strange thought, and Rikud's brain whirled once more down the tortuous course of half-formed questions and unsatisfactory answers. They were strangely shaped in some ways, and yet in others completely into being just for the moment and then abruptly passed into non-being again, something which was as impalpable as air. 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 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 had decided that they did not know where they were going, or why, and cogs in a great machine. Much of this Rikud could not understand, but he knew enough to realize that the reading machine had sided with the people against the elders, and it said the people had won. before Rikud's time, had negated the necessity for a knowledge of this was the only case of its kind, the exception to the rule, but it "Yes?" Almost no one read any more, and the library was heavy with the it But if he wasn't reading himself, Rikud usually went to sleep. All the people ever talked about was what they had done during the day, and it elbow. "What did you find out?" "Well, where's the book?" Rikud would read it tomorrow. changing." "Changing?" Crifer questioned the fuzzy concept as much as he questioned what it might mean in this particular case. "Yes, there are less of them, and one is bigger and brighter than the others." "I'm only saying what I read in the book," Crifer protested mildly. "Well, it's wrong. Variability and change are two words without meaning." 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. He shrugged and reserved the thought for later. He wanted to see the turn away. Here was an unknown factor which the perfect world failed that it spread out over almost the entire surface. Something big and round, all grays and greens and browns, and something for which Rikud had no name. of it had expanded outward and assumed the rectangular shape of the viewport, and its size as well. It seemed neatly sheered down the middle, so that on one side Rikud saw an expanse of brown and green, and on the other, blue. had ceased abruptly. Instead an ominous silence, broken at regular Change— and for a while he struggled with it. What he saw—what he had always not exist in through nothing but an obscuring cloud of white vapor, murky, swirling, more vapor. "What do you see?" "What else?" "Else? Nothing." Anger welled up inside Rikud. "All right," he said, "listen. What do the engines. "I'm hungry, Rikud." But that was silly. What were the gardens doing in the viewport? And besides, Rikud had the distinct feeling that here was something far vaster than the gardens, although all of it existed in the viewport which was no wider than the length of his body. The gardens, moreover, did. Nor did they spin. Nor did the trees grow larger with every jolt. it as fact. There—through the viewport and in it—was a garden. A never seen before, although he had always liked to stroll through the it was a garden. he admitted to Rikud. "But why should the garden be in the viewport?" 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 "It is an old picture of the garden," Chuls suggested, "and the plants It it was with a purpose—to eat, or to sleep, or perhaps to bathe in 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? "What's in here?" he demanded. "I know, but what's beyond it?" "Beyond it? Oh, you mean through it. It's only a door." There's nothing. It just isn't. It's only a door, Rikud." "No—" Rikud began, but the words faded off into a sharp intake of He missed the beginning, but then: —therefore, permit no unauthorized persons to go through this 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 gears and wheels and nameless things all strange and beautiful because "Odd," Rikud said aloud. Then he thought, "Now there's a good word, but no one quite seems to know its meaning." exist an endless succession of them, especially when the third one although it looked out on the garden, Rikud sensed that the topography He couldn't go alone. He'd die of the strangeness. It was a silly dry interested, yet the lame-footed man's mind was inadequate to cope with and Rikud found himself wishing that his friend had never read that the world," he said. "The library has a door and there is a door to the that. But there are no others." "Doing what?" "I imagined nothing. I'll show you—" "You'll show me nothing because I won't go." clearly. All else was bathed in a shadow of unreality. Rikud never wanted to do anything more than he wanted to open that darkness, something bright flashed briefly through the sky and was gone. All around Rikud were darkness and hunger and thirst. The buzzer did eat or drink. Rikud himself had fumbled through the blackness and the any more. The machinery, Rikud realized, also was responsible for food. "What won't?" "It was not bad. The world has moved through the blackness and the It was dark and he was hungry and everyone who was strong enough to run was chasing him, but every time he thought of the garden outside, and how big it was, the darkness and the hunger and the people chasing him But if he didn't open the door and go into the garden outside, he would voice didn't speak this time—through its door and into the place of

<question>:
What is not a theme explored in this story?

<options>:
A Change is necessary and inevitable for survival.
B Fear is a powerful motivator.
C Perception can often be all-encompassing.
D Equality must be realized.

<answer>:

D