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

<passage>:
TOLLIVER'S ORBIT was slow—but it wasn't boring. And it would get you there—as long as "Just don't try to sucker me in on the deal. I know you're operating something sneaky all through the colony, but it's not for me." The big moon-face of Jeffers, manager of the Ganymedan branch of Koslow Spaceways, glowered back at him. Its reddish tinge brightened the office noticeably, for such of Ganymede's surface as could be seen through the transparent dome outside the office window was cold, dim and rugged. The glowing semi-disk of Jupiter was more than half a million miles distant. orbiting Ganymede! "Try not to be simple—for once!" growled Jeffers. "A little percentage listen ! Maybe they live soft back on Earth since the mines and the Jovian satellite colonies grew but they were out here in the beginning, most of them. his body. It had been built for Ganymede, but not for Jeffers. whenever your contract's up. Think we'd bend a good orbit on your account?" Tolliver stared at him silently, but the other had difficulty meeting on a contract. Five hundred credits a week base pay, five hundred for hazardous duty. How else can you get pilots out to Jupiter?" "Okay I can't fire you legally—as long as you report for work," hazardous duty!" "Doesn't matter," answered Tolliver, grinning amiably. "The hazardous part is just being on the same moon as you for the next six months." He winked and walked out, deliberately leaving the door open behind him so as to enjoy the incoherent bellowing that followed him. He'll come around. I just want to get back to Earth with a clean rep. Let Jeffers and his gang steal the Great Red Spot off Jupiter if they like! It's their risk. Tolliver began to have his doubts the next day which was "Tuesday" by the arbitrary calender constructed to match Ganymede's week-long journey around Jupiter. His contract guaranteed a pilot's rating, but someone had neglected to specify the type of craft to be piloted. On the bulletin board, Tolliver's name stood out beside the number of one of the airtight tractors used between the dome city and the spaceport, or for hauling cross-country to one of the mining domes. Tolliver turned to see Red Higgins, a regular driver. "What do you mean?" "They say some home-office relative is coming in on the "What's wrong with that?" asked Tolliver. "Outside of the way they keep handing out soft jobs to nephews, I mean." orbit. Wait till you see the baggage you'll have to load!" Later in the day-period, Tolliver recalled this warning. Under a portable, double-chambered plastic dome blown up outside the ship's in stronger gravity than Ganymede's. Her trim coiffure was a shade too blonde which served to set off both the blue of her eyes and the cap "Sorry to keep you waiting," she said, sliding into the seat beside Tolliver. "By the way, just call me Betty." "Sure," agreed Tolliver thinking, Ohmigod! Trying already to be just "It's true enough," Tolliver assured her. "We need people out here, and it costs a lot to make the trip. They found they could send back loaded ships by 'automatic' flight—that is, a long, slow, economical orbit and automatic signalling equipment. Then they're boarded approaching Earth's orbit and landed by pilots who don't have to waste their time making the entire trip." He followed the signals of a spacesuited member of the port staff and maneuvered out of the dome. Then he headed the tractor across the frozen surface of Ganymede toward the permanent domes of the city. "How is it here?" asked the girl. "They told me it's pretty rough." "What did you expect?" asked Tolliver. "Square dances with champagne?" "Don't be silly. Daddy says I'm supposed to learn traffic routing and the business management of a local branch. They probably won't let me square inch of Ganymede is likely to be dangerous." from the city to the spaceport." "Don't sneer at Ganymede, honey!" he warned portentously. "Many a mission!" "You can call me Betty. What happened to him?" "I'll tell you some day," Tolliver promised darkly. "This moon can strike like a vicious animal." "Oh, they told me there was nothing alive on Ganymede!" deliberately dipped one track into an icy hollow. In the light gravity, the tractor responded with a weird, floating lurch. "Those slides," he continued. "Ganymede's only about the size of Mercury, something like 3200 miles in diameter, so things get heaped up at steep angles. When the rock and ice are set to sliding, they come at you practically horizontally. It doesn't need much start, and it and port. "It certainly is an honor to have you on Ganymede with us! That's all, he told me to find out what was wrong with operations on Ganymede. Betty, and Tolliver thought he muttered something about "just landed." After a moment, the big man came out of his daze enough to stab an In the gravity of Ganymede, the man was knocked off balance as much as yourself." "I'll come along with you, Tolliver," said the girl. "Let's not argue about it," said Betty, a trifle pale but looking determined. "I'm coming with you. Is that stuff getting soft yet?" Tolliver. "Why do you want them?" "Honey, I just don't think it will be so easy to lay hands on a dusty, moist air puffing out into the near-vacuum of Ganymede's nearest outcropping of rock. It promptly developed that she had something to learn about running on ice in such low gravity. Until they were out of direct line of sight from the settlement, Tolliver simply dragged her. Ganymede. They took one short rest, during which Tolliver was forced He ran a practiced eye over the board, reading the condition of the ship. It pleased him. Everything was ready for a takeoff into an economy orbit for Earth. He busied himself making a few adjustments, doing his best to ignore the protests from his partner in crime. He warned her the trip might be long. expectantly, and the man who flickered into life on the screen wore a uniform. "Space Patrol?" whispered Tolliver incredulously. "That's right," said Betty. "Uh ... Daddy made arrangements for me." Tolliver held her in front of the screen so she would not float out could arrange for a cruiser to escort his daughter to Ganymede and request as if he had been hanging in orbit merely until learning who to go down after. They really sent her out to nail someone , Tolliver realized. Of says it's set for a six-month orbit, or economy flight. Whatever they call it. I don't think he has any idea where we're headed." Tolliver pulled her back, holding her in mid-air by the slack of her The girl grinned. "Relax, Tolliver," she told him. "Did you really believe Daddy would send his own little girl way out here to Ganymede to look for whoever was gypping him?" "You ... you...?" "Sure. The name's Betty Hanlon. I work for a private investigating firm. If old Koslow had a son to impersonate—" "I'd be stuck for six months in this orbit with some brash young man," ! Can't they get us back? How can you tell where we're going?" "I know enough to check takeoff time. It was practically due anyhow, so we'll float into the vicinity of Earth at about the right time to be picked up." He went on to explain something of the tremendous cost in fuel the case in about three hours on Ganymede."

<question>:
What and where is Ganymede?

<options>:
A It’s a planet close to Earth.
B It’s a planet close to Jupiter.
C It’s a moon close to Mercury.
D It’s a moon close to Jupiter.

<answer>:

D