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

<passage>:
for fuel or supplies—it was more economical to purchase them in that era than to have them shipped from the future—he seldom went ashore, and then only at the urging of a newly assigned cousin anxious to see and felt an uncomfortable pang of a sensation he could no longer understand. "Where do you suppose Conrad has been all this time?" Martin idly asked the current cousin—who was passing as his nephew by now. The young man jumped, then glanced around him uncomfortably. "Conrad's a very shrewd fellow," he whispered. "He's biding his time—waiting until we're off guard. And then—pow!—he'll attack!" "Oh, I see," Martin said. He had often fancied that Conrad would prove to be the most stimulating member of the whole generation. But it seemed unlikely that he would Conrad?" ever have a chance for a conversation with the young man. More than one "Because he's coming to kill you." "Why should he kill me? I ain't done him nothing." promised five years before. "The whole thing's all my brother Conrad's fault. You see, he's an idealist," Raymond explained, pronouncing the last word with distaste. and his speech rather overbred, his mentors from the future having carefully eradicated all current vulgarities. "And Conrad really got upset over the way Earth has been exploiting the not so intelligent life-forms on the other planets," Raymond continued. "Which passing laws to do away with the—well, abuses and things like that, and I'm sure someday everything will come out all right. However, Conrad is so impatient." "I thought, in your world, machines did all the work," Martin suggested. "I've told you—our world is precisely the same as this one!" Raymond snapped. "We just come a couple of centuries or so later, that's all. worlds, it's far cheaper to use native labor than to ship out all that he had discovered that Raymond was perhaps the most intelligent of the lot. Somewhere in that relatively short span of time, his line or—more frightening—his race had lost something vital. Unaware of the near-contempt in which his young ancestor held him, Raymond went on blandly: "Anyhow, Conrad took it upon himself to feel particularly guilty, because, he decided, if it hadn't been for the fact that our great-grandfather discovered the super-drive, we "Oh, I do!" Martin said. He had pieced the whole thing together for himself long since, but he wanted to hear how Raymond would put it. "Unfortunately, Professor Farkas has just perfected the time transmitter. Those government scientists are so infernally officious—always inventing such senseless things. It's supposed to be hush-hush, but you know how news will leak out when one is always desperate for a fresh topic of conversation." Anyhow, Raymond went on to explain, Conrad had bribed one of Farkas' assistants for a set of the plans. Conrad's idea had been to go back in time and "eliminate!" their common great-grandfather. In that way, there would be no space-drive, and, hence, the Terrestrials would never get to the other planets and oppress the local aborigines. society in order to root out a single injustice?" "Not if it were a good one otherwise." "Well, there's your answer. Conrad got the apparatus built, or perhaps he built it himself. One doesn't inquire too closely into such matters. But when it came to the point, Conrad couldn't bear the idea of eliminating our great-grandfather—because our great-grandfather good man, you know." Raymond's expressive upper lip curled. "So Conrad decided to go further back still and get rid of his great-grandfather's father—who'd been, by all accounts, a pretty worthless character." a rush. "I wormed the whole thing out of him and all of us—the other cousins and me—held a council of war, as it were, and we decided it was our moral duty to go back in time ourselves and protect you." He beamed at Martin. The boy smiled slowly. "Of course. You had to. If Conrad succeeded in eliminating me, then none of you would exist, would you?" he had learned long ago that nobody did anything for nothing. But saying so was unwise. "We bribed another set of plans out of another of the professor's assistants," Raymond continued, as if Martin had answered, "and—ah—induced a handicraft enthusiast to build the gadget for us." Induced , Martin knew, could have meant anything from blackmail to the use of the iron maiden. "Then we were all ready to forestall Conrad. If one of us guarded you night and day, he would never be able to carry out his plot. So we made our counter-plan, set the machine as far back as it would go—and here wretched historical stint." exile," Raymond explained, "even though our life spans are a bit longer sad part: he already knew it wouldn't make a difference. Raymond clapped him on the shoulder. "I knew you weren't a sloppy sentimentalist like Conrad. Though you do have rather a look of him, you know." Suddenly that seemed to make Conrad real. Martin felt a vague stirring of alarm. He kept his voice composed, however. "How do you plan to protect me when he comes?" "How about a moat?" Martin suggested when they first came. "It seems to go with a castle." "Do you think a moat could stop Conrad?" Raymond asked, amused. "No," Martin smiled, feeling rather silly, "but it would make the place seem safer somehow." The threat of Conrad was beginning to make him grow more and more nervous. He got Raymond's permission to take two suits of armor that stood in the front hall and present them to a local museum, because several times he fancied he saw them move. He also became an adept with the ray gun and changed the surrounding landscape quite a bit with it, until Raymond warned that this might lead Conrad to them. During those early years, Martin's tutors were exchanged for the higher-degreed ones that were now needful. The question inevitably There was a loud, excited chorus of dissent. He chuckled inwardly. space travel yet. But we can go see this world. What's left of it. to ocean and from ocean to sea, touching at various ports and making they never moved back to land. Martin spent the rest of his life on The Interregnum . He felt curiously safer from Conrad there, although there was no valid reason why an ocean should stop a traveler through time. deported. himself. "Maybe it is worse, the way Conrad thinks. More planets "Oh," Martin murmured, trying to sound shocked, horrified—interested, even. "Sometimes I'm not altogether sure Conrad was wrong," Ives said, after a pause. "Tried to keep us from getting to the stars, hurting the people—I expect you could call them people—there. Still—" he smiled Conrad, and even he—" Ives looked out over the sea. "Must be a better way out than Conrad's," he said without conviction. "And everything couldn't even seem to care. During all this time, Conrad still did not put in an appearance. Martin had gotten to be such a crack shot with the ray pistol that he almost wished his descendant would show up, so there would be some excitement. the basic flaw in the elaborate plan they had concocted, it would have been Ives. However, when the yacht touched at Tierra del Fuego one bitter winter, Ives took a severe chill. They sent for a doctor from the future—one of the descendants who had been eccentric enough to continent, a hundred years or more before the date of his birth. they were afraid he might prove rather stuffy about the entire undertaking.

<question>:
How does Conrad go back in time?

<options>:
A Conrad stole Professor Farkas' time transmitter to send himself back in time.
B Professor Farkas sent him back in time with the time transmitter.
C Conrad built a time transmitter using a copy of Professor Farkas' plans.
D Professor Farkas' assistant sent Conrad back in time using the time transmitter after Conrad gave him a bribe.

<answer>:

C