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

<passage>:
"Don't!" Retief jumped—too late. Retief exhaled a plume of cigar smoke. "You're violating Terrestrial territory, Shluh," Retief said steadily. "Never mind the excuses," Retief said. "Just tell him I won't be "You're making a serious mistake, Shluh," Retief said. Mr. Retief to his quarters in this building—" "I don't advise you to violate my diplomatic immunity, Fith," Retief immunity in the case of Mr. Retief." "Don't be a fool, woman," Retief said. "Don't you see what you're "You think all women are fools, don't you, Mr. Retief?" She turned to the present government in power?" "I'm sure I haven't pried into—" "What about that Terrestrial cruiser? The one that disappeared out this Groaci. I certainly hope you're not thinking of openly intruding—" "Why?" "The Groaci are a very sensitive race. They don't welcome outworlders raking up things. They've been gracious enough to let us live down the fact that Terrestrials subjected them to deep humiliation on one occasion." "You mean when they came looking for the cruiser?" "I, for one, am ashamed of the high-handed tactics that were employed, grilling these innocent people as though they were criminals. We try never to reopen that wound, Mr. Retief." "They never found the cruiser, did they?" "Certainly not on Groac." Outside, Retief stood for a moment looking across at the deeply carved Retief studied the carving over the open doorways along the street. "To enjoy a cooling drink," Retief said in Groacian, squatting down at "To get the lead out," Retief said, placing a thick gold-piece in the Retief turned. A tall Groacian vibrated his mandibles in a gesture toward Retief. "To show this one in the streets, like all freaks." door. The other Groaci released him, hurried back inside. Retief looked "To not endure such insolence!" The Groacian advanced toward Retief. Retief backed away. head down, scuttled away. Retief backed into the opening to a narrow who followed, furious. Retief backed, rounded a corner into a narrow Retief stepped around him, seized his collar and yanked. The Groacian Retief put a foot against his chest and pushed. "Government men, I imagine. Word travels fast." Retief pulled off his indicative of rank rose as Retief entered the room. Neither offered a "Never mind that," Retief said. "These gentlemen didn't come here to Mr. Consul. I shall ask Shluh to recount it." He nodded to the police chief. "One hour ago," The Groacian said, "a Groacian national was brought to hospital suffering from serious contusions. Questioning of this individual revealed that he had been set upon and beaten by a "Have you ever heard," Retief said, looking steadily at Fith, "of a "Just keep that recorder going," Retief snapped. "All our efforts," Miss Meuhl said, "to live down that terrible episode! And you—" "Terrible? I understand that a Terrestrial task force stood off Groac and sent a delegation down to ask questions. They got some funny answers, and stayed on to dig around a little. After a week they left. Somewhat annoying to the Groaci, maybe—at the most. If they were innocent." "—to keep the Terrestrial consul and his staff in the dark," Retief Retief turned a steady look on Miss Meuhl. She closed her mouth. The back—about nine, I think—there was a little parade held here. Some curious looking creatures were captured. After being securely caged, they were exhibited to the gentle Groaci public. Hauled through the "How did they die?" Retief snapped. "Did you murder them, cut their "No!" Fith gasped. "I must correct this terrible false impression at once." "False impression, hell," Retief said. "They were Terrans! A simple narco-interrogation would get that out of any Groacian who saw the parade." "We'll deal with that question later," Retief said. "Right now, I want Retief stooped under the heavy timbers shoring the entry to the cavern. Retief walked along the raised wooden catwalk, studying the ship. Empty "How did you get it in here?" Retief asked. Retief grunted. "Let's go inside." Retief clambered up a narrow companionway, glanced around the interior Retief looked grimly at the slender Foreign Office official. "Where is "Where is that ship?" Retief rapped out. "You never learn, do you? "You can and you will, Fith," Retief said. "I intend to get to the four armed constables. They moved to ring Retief in. Retief eyed Fith. "Don't try it," he said. "You'll just get yourself in Retief looked at the four policemen. "I see your point," he said. "Miss Meuhl," Retief said, "I want you to listen carefully to what I'm "If you'll listen, you may find out," Retief said. "I have no time "You're still determined to make an issue of that incident!" Miss Meuhl snorted. "I really can hardly blame the Groaci. They are not a sophisticated race they had never before met aliens." happened nine years ago I'm concerned with. It's what's happening now. I've told you that it was only a lifeboat the Groaci have hidden out. Don't you understand the implication? That vessel couldn't have come far. The cruiser itself must be somewhere near by. I want to know where!" "The Groaci don't know. They're a very cultured, gentle people. You can "That's my decision," Retief said. "I have a job to do and we're the Groaci is to dispose of both of us. We're the only ones who know what happened. Fith almost did the job this afternoon, but I bluffed him out—for the moment." A force can be here in a week." "I'll do nothing of the sort! The Groaci are very fond of me! You ... Johnny-come-lately! Roughneck! Setting out to destroy—" "Blame it on me if it will make you feel any better," Retief said, "but Retief, rose and snapped on a light, turned to stare. "I got a little dirty. Don't worry about it." Retief went to his desk, "I have a message to get off first, Miss Meuhl," Retief said sharply. "That's right," Retief said calmly. "Now—" "Get that sender going, woman!" Retief snapped. "This is important." "I've already done so, Mr. Retief!" Miss Meuhl said harshly. "I've been "Mr. Retief," the face on the screen said, "I am Counsellor Pardy, Retief reached out and snapped off the communicator. The triumphant Retief went on earnestly, "I've found the missing cruiser." "Don't touch that screen," Retief said. "You go sit in that corner Retief ignored Miss Meuhl's fury as he spoke into the recorder. "Go ahead," Retief said. "Answer it."

<question>:
What is the conspiracy Retief is trying to uncover?

<options>:
A Nine years ago Groacians invaded Earth and stole a Terran space cruiser. Retief wants to find out what happened to it.
B Nine years ago, Consul Whaffle mysteriously disappeared from his government office. As the new consul, Retief feels it is his duty to find out what happened.
C Nine years ago, a Terran cruiser landed on Groac but soon mysteriously disappeared, along with its entire crew. Retief wants to find out what happened to the ship and its crew.
D Nine years ago Terrans came to Groac and attempted to take over the existing government, but failed. During the skirmish, a Terran cruiser disappeared. Retief wants to find out why the siege failed and what happened to the cruiser.

<answer>:

C