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

<passage>:
hush, and the ship jarred slightly as a thunderbolt slammed vengefully into its field. "Suppose we settle this argument about humanity," said Knof Llud Quest Quest III Quest III Quest Quest III's Quest voices, in tones of mingled eagerness and apprehension, of what might lie at the long journey's end. For the Quest III Quest III's but as the immense stores were spent and the holds became radioactively safe, the crew had spread identified it—no more." But this time the clamor was not to be settled. People pressed round were forgotten and exaltation prevailed. Knof Llud smiled wryly. The rest of the little speech he had been about to make didn't matter anyway, and it might have spoiled this moment. —and nothing will be the same. It won't be the same world we left, the world we knew and fitted in...." The captain put an arm round her with comforting pressure. "Don't worry. Things may have changed—but we'll manage." But his face had hardened against registering the gnawing of that same doubtful fear within him. He let his arm fall. "I'd better get up to the bridge. There's a new course to be set now—for Earth." He left her and began to climb the stairway again. Someone switched already set up on the calculator a course that would carry them to Earth. Llud nodded curt approval, remarking, "Probably we'll be intercepted Llud shook his head slowly. "Who knows? We don't know whether any of the other Quests returned successful, or if they returned at all. And we don't know what changes have taken place on Earth. It's possible—not likely, though—that something has happened to break civilization's continuity to the point where our expedition has been forgotten altogether." Lesra and the children—but somehow he didn't want to do that either. He felt empty, drained—like his ship. As the Quest III's strength had gone out of him. Now the last fuel compartment was almost empty and Captain Knof Llud felt tired and old. Perhaps, he thought, he was feeling the weight of his nine hundred Quest III Quest have been ringing in his ears. He rose, slipped the record back in its niche and picked out another, later, one. "We face the unpleasant realization that what was feared is probably true—that worlds such as the Sun's are a rare accident, and that we may complete our search without finding even one new Earth. "It makes no difference, of course we cannot betray the plan.... This may be man's last chance of escaping his pitiful limitation to one world in all the Universe. Certainly the building of this ship Quests . Perhaps our effort will prove as futile as pyramid-building, less practical than orgies of slaughter to reduce pressure.... In any case, it would be impossible to transport very many people to other stars its decline with the knowledge that its race went onward and upward, expanding limitlessly into the Universe.... "Hopeless, unless we find planets!" was from the time when he had grown philosophical after the first disappointments. He frowned thoughtfully, choosing one more spool that was only four Quest III Quest III Quests other expeditions failed also—will have reached a dangerously unstable phase, and before we can get back it may have collapsed completely from overpopulation. "Why go back, then with the news of our failure? Why not forget about Earth and go on to Omega Centauri? What use is quixotic loyalty to a decree five thousand years old, whose makers are dead and which may be forgotten back there? "Would the crew be willing? I don't know—some of them still show signs of homesickness, though they know with their minds that everything that was once 'home' has probably been swept away.... "It doesn't matter. Today I gave orders to swing the ship." Of all the western stars, until I die. Llud sighed. He still couldn't say just why he had given the order to turn back. The stars had claimed his heart—but he was still a part of Quest III's then felt a curious detached relief at the knowledge that after all these years he could still respond quickly and smoothly to a crisis. There was a moment's silence, and he heard the alarm start—three interstellar ship. Knowing that Gwar Den was still there, he said, "Now—attacked by what?" "Ships," said Gwar Den helplessly. "Five of them so far. No, there's a sixth now." Repeated blows quivered the Quest III's long enough to tell much." "If they're that small," said Knof Llud deliberately, "they can't carry anything heavy enough to hurt us. Hold to course. I'll be right up." "Something's happened," he judged with deadly twelve-year-old seriousness and, without wasting time on questions, "Can I go with you, Quest III Llud. "Well?" he snapped. "What are they doing?" Gwar Den spoke. "There are thirteen of them out there now, sir, and they're all banging away at us." from the same position. Knof Jr. flattened himself against the metal wall and watched silently. His young face was less anxious than his elders' he had confidence in his father. "If they had anything heavier," surmised the captain, "they'd have unlimbered it by now. They're out to get us. But at this rate, they can't touch us as long as our power lasts—or until they bring up some bigger stuff." The mild shocks went on—whether from projectiles or energy-charges, Quest III's Quest III Quest III the watchers for the brief moment in which its very atoms were torn apart. Knof Jr. whooped ecstatically and then subsided warily, but no one was paying attention to him. The men on the Quest III's Quest III Quests conquer. It became evident, too, that the bombardment was being kept up by a constant arrival of fresh attackers, while others raced away into space, presumably returning to base to replenish their ammunition. That argued a planned and prepared interception with virulent hatred behind it. Elsuz Llug, the gravitic engineer, calculated dismally, "At the rate we're having to shed energy, the fuel will be gone in six or eight hours." "We'll have reached Earth before then," Gwar Den said hopefully. "If they don't bring out the heavy artillery first." "We're under the psychological disadvantage," said the captain, "of not knowing why we're being attacked." Knof Jr. burst out, spluttering slightly with the violence of a thought too important to suppress, "But we're under a ps-psychological advantage, too!" hadn't made himself clear, "In a fight, if a guy gets mad he starts swinging wild and then you nail him." Smiles splintered the ice of tension. Captain Llud said, "Maybe you've got something there. They seem to be mad, all right. But we're not in a position to throw any punches." He turned back to the others. "As I was going to say—I think we'd better try to parley with the enemy. At least we may find out who he is and why he's determined to smash us." Quest III multiplied demands. Those outside were squandering vastly greater amounts of energy in the effort to batter down its defenses, but converting that energy into harmless gravitic impulses was costing the Quest III nerves and muscles and will weakening along with the power-sinews of his ship. ," interrupted a harshly crackling voice with a strange accent, " and pleading will do you no good. " absurdly with the same words in his own voice on the still repeating tape. He snapped off the record last. The two other interstellar expeditions that went out have already returned and been destroyed, as you will soon be—the sooner, if you continue toward Earth." Quest

<question>:
Why were three Quest ships built?

<options>:
A To have a better chance of success if any failed.
B So each could travel for 20,000 years.
C To transport more people to the new planet.
D In case the others break down.

<answer>:

A