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

<passage>:
Galaxy Science Fiction September 1951. should . This was why the world had moved When nobody aboard ship remembers where it's across the darkness and the stars for all Rikud's lifetime and more. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] But he was afraid. going, how can they tell when it has arrived? the great changeless sweep of space. He could not quite explain the feelings within him they were so alien, so unnatural. But ever since the engines somewhere in the rear of the world had changed their tone, realized this odd difference in himself, he kept it locked up inside him. Today, space looked somehow different. The stars—it was a meaningless everyone fled before him. He stumbled again in the place of the concept to Rikud, but that was what everyone called the bright "Where's the buzzer?" he sobbed. "I must find the buzzer." ignored it. But it came again, and each time it left him with a feeling embroiled him in a hopeless, infinite confusion that left him with a explain had entered the elder man's head for a moment, but it had departed almost before Chuls knew of its existence. "I'll go with you," Rikud told him. A hardly perceptible purple glow pervaded the air in the room of the Near the ship, water that did not come from a machine gurgled across the land, and Rikud lay down and drank. It was cool and good, and when he got up, Crifer and Wilm were outside the world, and some of the others followed. They stood around for a long time before going to the water to drink. There was a strange thought, and Rikud's brain whirled once more down the tortuous course of half-formed questions and unsatisfactory answers. That is, if those creatures coming from the ship are people." He had even wondered what it was like to get hurt. No one ever got 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. there should have been authority. A long time ago the reading machine in the library had told him of the elders—a meaningless term—who had 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 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 he knew enough to realize that the reading machine had sided with the look of easy contentment on Chuls' face as the rays fanned down upon him, bathing his old body in a forgotten magic which, many generations before Rikud's time, had negated the necessity for a knowledge of medicine. But when, in another ten years, Chuls would perish of old age, the rays would no longer suffice. Nothing would, for Chuls. Rikud often thought of his own death, still seventy-five years in the future, not without a sense of alarm. Yet old Chuls seemed heedless, with only a decade to go. meant that, in the two unoccupied hours before sleep, he went to the called astronomy, I think." This was a new thought to Rikud, and he propped his head up on one elbow. "What did you find out?" "That's about all. They're just called astronomy, I think." "Well, where's the book?" Rikud would read it tomorrow. knew his lame-footed companion understood the word no better than he did. channelings of Rikud's energy in new and confusing directions. 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 to control. But how could a star change into a blinking blue-white Rikud couldn't remember, and he suddenly wished he could read Crifer's book on astronomy, which meant the same as stars. Except that it was But the new view persisted. Of stars there were few, and of the blackness, almost nothing. Gone, too, was the burning globe. Something loomed there in the port, so huge Startled, Rikud leaped back. The sullen roar in the rear of the world "Won't you eat, Rikud?" Chuls called from somewhere down below. nothing but an obscuring cloud of white vapor, murky, swirling, more confusing than ever. "Chuls," he called, remembering, "come here." the engines. "I'm hungry, Rikud." It changed. Where are the stars? Where are they, Chuls, if it did not change?" 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 if everyone lived as if the world still stood in blackness, how could they find the nature of that purpose? machine and book on astronomy or stars in his lap, Rikud approached the door. "I think so." "You can't, probably. How can anyone go where no one has been before? 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 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 exist an endless succession of them, especially when the third one opened on a bare tunnel which led to yet another door. What would he do out in the garden? He couldn't go alone. He'd die of the strangeness. It was a silly thought no one ever died of anything until he was a hundred. Rikud and Rikud found himself wishing that his friend had never read that book on astronomy. "Why don't we go see?" he suggested. Then, confused, he frowned. What would they do if the buzzer stopped buzzing? 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 crashing sound. He looked as the gears and cogs and wheels crumbled beneath them. But everything was so dark that only the stars shone clearly. All else was bathed in a shadow of unreality. when he pressed his face close against the viewport, there in the 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 whimpering to the dining room, his tongue dry and swollen, but the smooth belt that flowed with water and with savory dishes did not run "What won't?" "The buzzer will never sound again. I broke it." and the feet pounding behind him, and he wanted only to get away. die because he had no food and no water and his stomach gurgled and grumbled and hurt. And everyone was chasing him. He stumbled through the darkness and felt his way back to the library, far away, and he knew they would come after him because they wanted to break him.

<question>:
What caused the ship to leave its planet initially?

<options>:
A There was a shortage of women, and the main characters were sent to find mates.
B The reason is never disclosed.
C The planet they were from ran out of viable resources.
D They are explorers who got lost, and their fate was to drift the universe.

<answer>:

B