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 "Great!" muttered Betty. "What a lucky girl I am!" "Yes," admitted Tolliver, "there I'll explain how I cut the fuel flow and see if she's detective enough to suspect that we're just orbiting Ganymede! "You asked any of them lately?" Tolliver prodded. Tolliver rammed his fists into the side pockets of his loose blue can't quit." Jeffers fidgeted in his chair, causing it to creak under the bulk of his body. It had been built for Ganymede, but not for Jeffers. Tolliver stared at him silently, but the other had difficulty meeting that way, either you get in line with us or you're through right now!" "You can't fire me," retorted the pilot pityingly. "I came out here 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," "Doesn't matter," answered Tolliver, grinning amiably. "The hazardous part is just being on the same moon as you for the next six months." 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 On the bulletin board, Tolliver's name stood out beside the number Later in the day-period, Tolliver recalled this warning. Under a 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 apparently won from one of the pilots. She wore gray slacks and a heavy Tolliver. "By the way, just call me Betty." "It's true enough," Tolliver assured her. "We need people out here, and 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?" see much else." "You never can tell," said the pilot, yielding to temptation. "Any square inch of Ganymede is likely to be dangerous." I'll be sorry later , he reflected, ?" Tolliver pursed his lips and put on a shrewd expression. "Don't sneer at Ganymede, honey!" he warned portentously. "Many a man who did isn't here today. Take the fellow who used to drive this 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!" you'd least expect. That's why I draw such high pay for driving an unarmored tractor." 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 Tolliver! he was drawing the salary of a space pilot. Betty looked thoughtful. "I'm retiring in six months if I'm still alive," he said bravely, edging the tractor into the airlock at their destination. "Made my "Miss Koslow!" he beamed, like a politician the day before the voting. "It certainly is an honor to have you on Ganymede with us! That's all, Tolliver, you can go. Yes, indeed! Mr. Koslow—the president, that is: your father—sent a message about you. I repeat, it will be an honor to Tolliver. "We won't be working together, I'm afraid. You've already had Tolliver blinked. He had taken her for three or four years older. "Daddy gave me the title of tenth vice-president mostly as a joke, when he told me to find out what was wrong with operations on Ganymede. I have some Betty, and Tolliver thought he muttered something about "just landed." Tolliver, hardly thinking about it, expected the someone to be Tolliver brought up a snappy uppercut to the man's chin, feeling that it was a poor time to engage Jeffers in fruitless debate. In the gravity of Ganymede, the man was knocked off balance as much as he was hurt, and sprawled on the floor. "I Betty. The others were swarming over Tolliver. Jeffers came around his Tolliver found himself dumped on the floor of an empty office in the Tolliver grunted. Sorrow would not reduce the throbbing, nor was he "Thanks for letting me know in time," said Tolliver. "Your paycheck," said Betty. "As soon as I saw that ridiculous amount, Tolliver groaned. "Sure!" grumbled the pilot. "He thinks I told you he was grafting or "What do you know about the crooked goings-on here?" asked Betty after "Nothing," retorted Tolliver. "Except that there are some. There are rumors, and I had a halfway invitation to join in. I think he sells things to the mining colonies and makes a double profit for himself by "What do you think you're up to?" asked Betty with some concern. "I'll come along with you, Tolliver," said the girl. Tolliver. with some good lie that will keep me from getting through." Through the faceplates, he saw the girl nod, wide-eyed. As soon as he plunged the knife into the outer layer, he could see dusty, moist air puffing out into the near-vacuum of Ganymede's surface. Fumbling, he cut as fast as he could and shoved Betty through the small opening. , Tolliver reminded himself. Then, when he decided that it was safe enough to pause and tell her Ganymede. They took one short rest, during which Tolliver was forced to explain away the dangers of slides and volcanic puffballs. He admitted to having exaggerated slightly. In the end, they reached the "That's all right," Tolliver told the girl. "We can get in with no the time required to seal, pump air and open the inner hatch and then "Who knows?" retorted Tolliver. "There wasn't time to check Tolliver sighed. In their weightless state, it was no easy task to pry When Betty produced a memo giving frequency and call sign, he set about exasperatedly at a bulkhead, marveling at the influence of a man who could arrange for a cruiser to escort his daughter to Ganymede and For one thing, though the officer seemed well acquainted with Betty, he , Tolliver realized. "We do have one trouble," he heard Betty saying. "This tractor driver, Tolliver, saved my neck by making the ship take off somehow, but he 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 "Miss Koslow?" repeated the spacer. "Did she tell you—well, no matter! "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?" "I'd be stuck for six months in this orbit with some brash young man," Tolliver finished for her. "I guess it's better this way," he said "I didn't expect to so soon." "Yeah, you were pretty lucky. They'll think you're a marvel to crack the case in about three hours on Ganymede."

<question>:
What did Tolliver tell Betty that was actually true?

<options>:
A he regularly drives armored vehicles on missions
B the rock and ice slides kill people often
C volcanic puffballs pop out through the frozen crust
D how much he's making to work on Ganymede

<answer>:

D