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

<passage>:
Tr'en were an efficient people. All the preliminary reports had agreed on that Planets. An invitation, the Comity was sure, which the Tr'en would not accept. Korvin stretched out on the cell's single bunk, a rigid affair which was hardly meant for comfort, and sighed. He'd had three days of In any decently-run jail, he told himself with indignation, there would at least have been other prisoners to talk to. But on Tr'en True, every night the guards came in and gave him a concentrated lesson in the local language, but Korvin failed to get much pleasure out of that, being unconscious at the time. But now he was equipped to discuss almost anything from philosophy to plumbing, but there was nobody to discuss it with. He changed position on the bunk and stared at the walls. The Tr'en were efficient As he reached this dismal conclusion, the cell door opened. Korvin got up off the bunk in a hurry and spun around to face his visitor. The Tr'en was tall, and slightly green. there might be almost anything else hidden and ready to fire on him. "What do you want with me?" Korvin said. The Tr'en speech—apparently there was only one language on the planet—was stiff and slightly awkward, but easily enough learned under drug hypnosis as it did the disclosure of the Tr'en fifty-eight teeth, mostly pointed. Korvin stared back impassively. "I have been ordered to come to you," Didyak said, "by the Ruler. The Ruler wishes to talk with It wasn't quite "talk" that was a general word in the Tr'en language, and Didyak had used a specific meaning, roughly: "gain information from, by peaceful and vocal means." Korvin filed it away for future reference. "Why did the Ruler not come to me?" Korvin asked. "The Ruler is the Ruler," Didyak said, slightly discomfited. "You are Korvin shrugged, sighed and smoothed back his hair. "I obey the command of the Ruler," he said—another ritual. Everybody obeyed the command of the Ruler. If you didn't, you never had a second chance to try. But Korvin meant exactly what he'd said. He was going to obey the commands of the Ruler of the Tr'en—and remove the Tr'en threat from the rest of the galaxy forever. Korvin decided, much too much of a bad idea, even when the color contrast of the Tr'en themselves were figured in. The Ruler himself, a Tr'en over seven feet tall and correspondingly broad, sat in the great chair, his four fingers tapping gently on the table near him, staring at Korvin and his guards. The guards stood on either side of their captive, looking as impassive as jade statues, six and a half feet high. Korvin wasn't attempting to escape. He wasn't pleading with the Ruler. He wasn't defying the Ruler, either. He was just answering questions. The Tr'en liked to have everything clear. They were a logical race. The Ruler had started with Korvin's race, his name, his sex—if any—and whether or not his appearance were normal for humanity. "Within what limits?" Korvin shrugged. "Some are over eight feet tall," he said, "and others under four feet." He used the Tr'en measurement scale, of course it "Approximately?" the Ruler growled. "We ask for precision here," he said. "We are scientific men. We are exact." Korvin nodded hurriedly. "Our race is more ... more approximate," he said apologetically. "Undoubtedly," Korvin agreed politely. "I'll try to do the best I can for you." "You will answer my questions," the Ruler said, "with exactitude." He straps. It was obviously a form of lie-detector—and Korvin felt match their enormous command of the physical universe adapting a hypnopædic language-course to an alien being so quickly had been wonder enough, but adapting the perilously delicate mechanisms that necessarily made up any lie-detector machinery was almost a miracle. He hoped the lie-detector had been adjusted correctly. If it showed continue." Korvin swallowed again. The test hadn't really seemed extensive enough to him. But, after all, the Tr'en knew their business, better than anyone else could know it. They had the technique and the logic and the training. He hoped they were right. The Ruler was frowning at him. Korvin did his best to look receptive. "I have told the truth," Korvin said. "But it is not—not the truth we want," the Ruler said. Korvin shrugged. "I replied to your question," he said. "I did not Ruler," he said at last, in an approximation of his usual one. "But the Ruler will not be confused. We have experts in matters of logic"—the Tr'en word seemed to mean right-saying —"who will advise the Ruler. They will be called." Korvin's guards were standing around doing nothing of importance now that their captor was strapped down in the lie-detector. The Ruler gestured and they went out the door in a hurry. The Ruler looked down at Korvin. "You will find that you cannot trick us," he said. "You will find that such fiddling"— translated—"attempts will get you nowhere." Korvin devoutly hoped so. The experts in logic arrived shortly, and in no uncertain terms Korvin were so much primer material for the Tr'en. "They can be treated mathematically," one of the experts, a small emerald-green being, told Korvin thinly. "Of course, you would not understand the mathematics. But that is not important. You need only understand that we cannot be Korvin was very glad that wasn't a question. It was, after all, the "Sometimes," Korvin said. "It has other names?" the Ruler said. "It has no name," Korvin said truthfully. The Tr'en idiom was like the Earthly one The key question had, at last, been asked. Korvin felt grateful that the logical Tr'en had determined to begin from the beginning, instead "True," Korvin said again. The ruler sighed gently. "Explain this governor to us," he said. Korvin shrugged. "The explanation cannot be given to you." The Ruler turned to a group of his experts and a short muttered conversation took place. At its end the Ruler turned his gaze back to "I will not," Korvin said. It was the signal for another conference. With some satisfaction, Korvin noticed that the Tr'en were becoming slightly puzzled they were no longer moving and speaking with calm assurance. Korvin shook his head earnestly. "I am attempting," he said, "not to confuse you." "Then I ask for an answer," the Ruler said. The Ruler beckoned to a heavy-set green being, who stepped forward from a knot of Tr'en, inclined his head in Korvin's direction, and Korvin shook his head. "If you insist," he said, "I'll try it. But you won't understand it." The Ruler frowned. "We shall understand," he said. "Begin. Who governs you?" "None," Korvin said. the technicians handling the lie-detector. Korvin turned to see their the lie-detector was telling them, It took three days—but boredom never really had a chance to set in. Korvin found himself the object of more attention than he had hoped for insoluble. And the Tr'en weren't capable of that sort of thinking. Korvin thanked his lucky stars that their genius had been restricted

<question>:
How was Korvin able to avoid disclosing the true intent of his mission under the lie detector questioning?

<options>:
A While he was strapped down in the lie-detector, Korvin subtly switched the wire that indicated a truth with the one that indicated a lie.
B Korvin said truths that literally answered the Tr'en's questions but evaded the intent behind their questions. .
C The Tr'en hadn't tested the lie-detector extensively enough and the machine was faulty.
D Even with the Tr'en's language lessons, Korvin could only to speak in very simple terms and was unable to answer the Ruler's questions at the depth the Ruler was expecting.

<answer>:

B