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

<passage>:
mathematical prodigy, but dying of an incurable disease? She collected Matheny stared out the wall, his hands twisting nervously behind his disease. So do you and I. Every day we grow older." "Uh!" exclaimed Doran. on top and tight around the hips. After all, some of the men who knew her private number were important. would have been too presumptuous. He was talking to an Earthman, who had heard everything already. "Yes?" Matheny faced around, shivering with his own tension. "So? Since when has all Mars had as much spending money as one big-time awful headache and can't see Mr. Sastro tonight. Where you at, Gus?" The gravity was not as hard to take as Peter Matheny had expected. Three generations on Mars might lengthen the legs and expand the chest a trifle, but the genes had come from Earth and the organism readjusts. What set him gasping was the air. It weighed like a ton of wool and had apparently sopped up half the Atlantic Ocean. Ears trained to listen through the Martian atmosphere shuddered from the racket conducted by Earth's. The passport official seemed to bellow at him. visitors to Earth and I assure you, sir, an ordinary five-year visa chuckled patronizingly. "I am afraid, sir, you won't find many people who wish to leave. They wouldn't be able to see the Teamsters Hour on Mars, would they?" "Oh, we don't expect immigration," said Matheny shyly. He was a fairly young man, but small, with a dark-thatched, snub-nosed, gray-eyed head that seemed too large for his slender body. "We learned long ago that no one is interested any more in giving up even second-class "Thanks," said Matheny, "but, you see, I—we need—that is.... Oh, before I hit the pavement! The August twilight wrapped him in heat and stickiness. He could see temperature wasn't too far below zero. Why did they tap me for this job? he asked himself in a surge of years out of date. He should find himself a hotel, he thought drearily, but he wasn't tired the spaceport would pneumo his baggage to him The city roared at him. He fumbled after his pipe. Of course , he told himself, that's why few spins of roulette soothing: it was always an intellectual challenge more, he would have been among people he understood. The frightful thing about the Earthman was the way he seemed to exist only in organized masses. A gypsy snake oil peddler, plodding against, say, the Grant, Harding &amp Adams Public Relations Agency. Matheny puffed smoke and looked around. His feet ached from the weight on them. Where could a man sit down? It was hard to make out any "I—I'm not hungry," stammered Matheny. "I just wanted to sit in—" "Hm?" said Matheny. or too deep for him. He'd have to relax with a crap game instead. He had been standing at the table for some time before the rest of the congregation really noticed him. Then it was with awe. The first few passes he had made were unsuccessful. Earth gravity threw him off. "Oh—I see—excuse me, I, I, I—" Matheny backed out of the crowd, shuddering. He looked around for some place to hide his burning ears. "You forgot your chips, pal," said a voice. "Oh. Thanks. Thanks ever so much. I, I, that is—" Matheny cursed his knotting tongue. Damn it, just because they're so much more sophisticated than I, do I have to talk like a leaky boiler? The helpful Earthman was not tall. He was dark and chisel-faced and sleekly pomaded, dapper in blue pajamas with a red zigzag, a sleighbell Matheny had yet heard. Matheny sighed. "A drink is what I need the very most." "There aren't many of us on Earth," agreed Matheny. "Just a small "I should think you would do a lot of traveling here. The old mother planet and so on." "We can't afford it," said Matheny. "What with gravitation and distance, such voyages are much too expensive for us to make them for pleasure. Not to mention our dollar shortage." As they entered the "Trouble with it is, I hear Mars is not so comfortable," said Doran. "I air to keep a man alive. And there are no cities, just little towns and villages and ranches out in the bush. I mean you are being pioneers and making a new nation and all that, but people paying half a megabuck for "I do know," said Matheny. "But we're poor—a handful of people trying to make a world of dust and sand and scrub thorn into fields and woods Grill, on the 73rd Level. Matheny's jaw clanked down. Matheny followed Doran past a sign announcing that this show was for purely artistic purposes, into a booth. There a soundproof curtain reduced the noise level enough so they could talk in normal voices. "What'll you have?" asked Doran. "It's on me." "Oh, I couldn't let you. I mean—" "Nonsense. Welcome to Earth! Care for a thyle and vermouth?" Matheny shuddered. "Good Lord, no!" why do you call yourselves poor?" "Because we are," said Matheny. "By the time the shipping costs have been paid on a bottle, and the Earth wholesaler and jobber and sales on Mars. The same principle is what's strangling us on everything. Old "It was our mainstay," admitted Matheny, "but it's been overworked. to, well, attract capital from Earth?" "Of course," said Matheny bitterly. "We offer the most liberal Matheny shrugged. "I haven't told you anything that isn't known to The beer arrived. Matheny engulfed himself in it. Doran sipped at a Matheny's finger stabbed in the general direction of Doran's pajama Matheny felt his eloquence running down and grabbed for the second he laughed at Matheny's, though they were probably too rustic for a strangely, my friend. Say on." "No." Matheny realized his head was a bit smoky. The walls of the booth seemed odd, somehow. They were just leatheroid walls, but they had an odd quality. "No, sorry, Gus," he said. "I spoke too much." "Whoof!" Matheny sat down. The chair slithered sensuously about his contours. He jumped. "What the dusty hell—Oh." He tried to grin, but his face burned. "I see." "Me?" Matheny heard his voice climb to a schoolboy squeak. "Me? Exotic? Why, I'm just a little college professor. I g-g-g, that is—" His tongue got stuck on his palate. He pulled it loose and moistened uncertain lips. abandoned canal." "What's a bushcat? And we don't have canals. The evaporation rate—" While Matheny jittered about, shaving and showering and struggling with slipstring. A con man, you would call it." "Forget that. Please. I spoke out of turn." "What?" Matheny gaped out of the bathroom. Matheny hesitated. If only he hadn't taken that last shot! It made him he became overcautious. They had instructed him on Mars to take chances if he must. "I could tell you a thing or two that might give you a better idea," he "What? But—but—" Matheny hung onto himself and tried to believe that "I know." Matheny stared, embarrassed, at the carpet. "I'm sorry "Oh, it's simple enough," said Matheny. "It's only that we already are haul," said Matheny. "Not many Terrestrial archeologists get to Mars

<question>:
For Matheny, what was the hardest part about being on Earth?

<options>:
A The higher gravity hurt his feet when he walked
B His outdated clothes embarrassed him
C The officials yelling at him upset him
D The thicker air was hard to breathe

<answer>:

D