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 their efficiency, as a matter of fact, was what had made 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. He looked, as all the Tr'en did, vaguely humanoid—that is, if you don't bother to examine him closely. Life in the universe appeared to really didn't care about it it was none of his business. The Tr'en regarded him narrowly through catlike pupils. "You are Korvin," he said. It was a ritual, Korvin had learned. "You are of the Tr'en," he replied. The green being nodded. "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 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 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 to go to him. Such is his command." 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. That, after all, was his job. 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 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 "Slipshod," the Ruler muttered. "You will answer my questions," the Ruler said, "with exactitude." He "We do," the Ruler told him. "We are an exact and a scientific race. A The Tr'en, under other circumstances, would have been a valuable addition to the Comity of Nations. Being what they were, though, they could only be a menace. And ?" the Ruler asked. A "I am not," he said. The Ruler looked to his technicians for a signal, and nodded on The technicians gave another signal. The Ruler looked, in his frowning "Why did you land your ship on this planet?" the Ruler said. The Ruler blinked. "Very well," he said. "Was your job ended when the ship crashed?" The Tr'en word, of course, wasn't ended "What else does your job entail?" the Ruler said. The Ruler roared. "Do not waste time with the obvious!" he shouted. "But it is not—not the truth we want," the Ruler said. the truth, just as the Ruler is the Ruler?" "I—" The Ruler stopped himself in mid-roar. "You try to confuse the 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 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 The Ruler looked down at Korvin. "You will find that you cannot trick the secretary of the club whose members were secretaries, Achilles and the tortoise, and all the other lovely paradox-models scattered around were so much primer material for the Tr'en. "They can be treated "The name of your planet is Earth?" the Ruler asked. A few minutes had "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 "Do you know its location?" the Ruler said. "And you will tell us about it?" the Ruler went on. Very sharp, Korvin told himself grimly. "It is," he said. "Then the government which reigns over several planets is supreme," the Ruler said. "It is," Korvin said. "Who is it that governs?" the Ruler said. The key question had, at last, been asked. Korvin felt grateful that the logical Tr'en had determined to begin from the beginning, instead are governed, you have said," the Ruler went on. "Then there is a governor for this system," the Ruler said. The ruler sighed gently. "Explain this governor to us," he said. 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 The Ruler had finished his conference. "You are attempting again to "Then I ask for an answer," the Ruler said. The Ruler hesitated, then nodded. "Ask it," he said. "We shall answer 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 began. "Our government is the only logical form of government," he said in a high, sweet tenor. "The Ruler orders all, and his subjects obey. In this way uniformity is gained, and this uniformity aids in the speed of possible action and in the weight of action. All Tr'en act instantly in the same manner. The Ruler is adopted by the previous Ruler "You have heard our government defined," the Ruler said. "Now, you The Ruler frowned. "We shall understand," he said. "Begin. Who governs you?" "Then there is a governor," the Ruler insisted. "Then there is no government," the Ruler said. "There is no single "Who makes them binding?" the Ruler asked. "Who forces you to accept "It is a defect in your explanation," the Ruler almost snarled. "But with no single ruler to form policy, to make decisions—" democracy ," Korvin said. "It means the rule of the people. There is no need for another ruler." One of the experts piped up suddenly. "The beings themselves rule each other?" he said. "This is clearly impossible 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 Mission accomplished the Tr'en aren't about to come marauding out into space too soon. They've been given food

<question>:
How did the Ruler become the Ruler?

<options>:
A He was adopted by the previous Ruler.
B He overthrew the previous Ruler.
C He is the biological son of the previous Ruler.
D He was elected as Ruler by the Tr'en.

<answer>:

A