question:  Why did the Groacians hide the ship?
context: You don't have to be crazy to be an earth diplomat—but on Groac it sure helps! [Transcriber's Note: This etext was produced from Worlds of If Science Fiction, March 1962. I've been tied up every off-duty hour since I got here—" "You can't offend the Groaci," Miss Meuhl said sharply. "You've been here on Groac for four years, Miss Meuhl. "The Groaci are a very sensitive race. The pale-featured Groacian vibrated his throat-bladder in a distressed bleat. "The impossibility of access to outworlders. Outside, Retief stood for a moment looking across at the deeply carved windowless stucco facades lining the street, then started off in the direction of the Terrestrial Consulate General. The few Groacians on the street eyed him furtively, veered to avoid him as he passed. An elaborate one picked out in pinkish paint seemed to indicate the Groacian equivalent of a bar. A Groacian bartender was dispensing clay pots of alcoholic drink from the bar-pit at the center of the room. The other Groaci released him, hurried back inside. Retief backed, rounded a corner into a narrow alley-like passage, deserted, silent ... except for the following Groacian. Two Groaci wearing heavy eye-shields and elaborate crest ornaments indicative of rank rose as Retief entered the room. "One hour ago," The Groacian said, "a Groacian national was brought to hospital suffering from serious contusions. "Have you ever heard," Retief said, looking steadily at Fith, "of a Terrestrial cruiser, the ISV Terrific , which dropped from sight in this sector nine years ago?" I understand that a Terrestrial task force stood off Groac and sent a delegation down to ask questions.
output:  They were afraid to admit they knew where it was.
options:  To overthrow the government.  They wanted to hide the Terrestrials as long as they could.  They were afraid to admit they knew where it was.  They wanted to keep it for further research.