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 Tr'en were an efficient people. All the preliminary reports had agreed on that their efficiency, as a matter of fact, was what had made 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 isolation, with nothing to do but explore the resources of his own mind. He'd tried some of the ancient Rhine experiments, but that was no good he still didn't show any particular psi talents. He couldn't unlock the cell door with his unaided mind he couldn't even alter the to the wonder and amazement of his Tr'en captors. He could do, as a matter of fact, precisely nothing. He wished quietly that the Tr'en had seen fit to give him a pack of cards, or a book, or even a folder of tourist pictures. The Wonders of Tr'en, according to all the advance reports, were likely to be pretty boring, but they'd 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 Korvin was all alone. 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 there weren't even any He wasn't tired and he wasn't hungry his captors had left him with a full stock of food concentrates. up off the bunk in a hurry and spun around to face his visitor. The Tr'en was tall, and slightly green. Korvin didn't Korvin," he said. "I am Didyak of the Tr'en," he said. Amenities over with, he relaxed slightly—but no more than slightly—and came into the cell, closing the door behind him. Korvin thought of jumping the Tr'en, but decided quickly against it. He was a captive, and it was unwise to assume that his captors had no more resources than the ones he saw: a small translucent pistollike affair in a holster at the Tr'en's side, and a "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 it was the most rigorously logical construction of its kind Korvin had ever come across. It reminded him of some of the mathematical metalanguages he'd dealt with back on Earth, in training to get the hang of, Korvin told himself bitterly. He thought for a 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. Korvin shrugged, sighed and smoothed back his hair. "I obey the 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. That, after all, was his job. 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. Korvin nodded hurriedly. "Our race is more ... more approximate," he straps. It was obviously a form of lie-detector—and Korvin felt 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. The Tr'en, under other circumstances, would have been a valuable He hoped the lie-detector had been adjusted correctly. If it showed him telling an untruth, he wasn't likely to live long, and his job—not to mention the strongest personal inclinations—demanded most 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. Korvin looked sober. "Yes," he said. Korvin shrugged. "I replied to your question," he said. "I did not the Ruler will not be confused. We have experts in matters of logic"—the Tr'en word seemed to mean 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. The expert frowned horribly, showing all of his teeth. Korvin did his "Sometimes," Korvin said. "It has other names?" the Ruler said. "It has no name," Korvin said truthfully. The Tr'en idiom was like the The key question had, at last, been asked. Korvin felt grateful that the logical Tr'en had determined to begin from the beginning, instead of going off after details of armament first Korvin shrugged. "The explanation cannot be given to you." Korvin. "Is the deficiency in you?" he said. "Are you in some way Korvin noticed that the Tr'en were becoming slightly puzzled they were no longer moving and speaking with calm assurance. "Then the machine is faulty," the expert said. "It will be corrected." Korvin wondered, as the technicians argued, how long they'd take studying the machine, before they realized it didn't have any defects to correct. He hoped it wasn't going to be too long he could foresee another stretch of boredom coming. And, besides, he was getting 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 It wasn't very difficult he hadn't thought it would be. Even the most logical of thinking beings has a subconscious as well as a conscious mind, and one of the ways of dealing with an insoluble problem is to and killing the problem's main focus was a little more complicated. That couldn't be done by the subconscious mind the conscious had to problem was insoluble. And the Tr'en weren't capable of that sort of thinking. Korvin thanked his lucky stars that their genius had been restricted to the physical and mathematical. Any insight at all into the mental sciences would have given them the key to his existence, and his entire plan, within seconds. But, then, it was lack of that insight that had called for this particular plan. That, and the political structure of the Tr'en. The same lack of insight let the Tr'en subconscious work on his escape without any annoying distractions in the way of deep reflection. Someone left a door unlocked and a weapon nearby—all he was airborne, and then space-borne, inside of a few hours after leaving the cell. He set his course, relaxed, and cleared his mind. He had no psionic messages, but he could send them. He sent one now. Mission accomplished the Tr'en aren't about to come marauding out into space too soon. They've been given food for thought—nice indigestible food that's going to stick in can't digest it and stay what they are you've got to be democratic, to some extent, to understand the idea. What

<question>:
Why does the text mean when it says that Korvin was "unconscious" at the time of his lessons in the local language?

<options>:
A It means that the Tr'en put Korvin under drug hypnosis while they taught him their language.
B It means that he was so bored out of his mind  during the language lessons that he was hardly conscious.
C It means that the Tr'en came into Korvin's cell while he slept in order to use their advanced technology which quickly teaches the unconscious mind.
D It means that the Tr'en knocked him out every night in order to use their advanced technology which quickly teaches the unconscious mind.

<answer>:

A