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

<passage>:
The planet itself was tough enough—barren, desolate, in for twenty hours, and then we're going back out there to finish that search-pattern. Earth needs uranium, honey, and I know you'd never be happy quitting in the middle translucent skin of the Dome, and I felt sick. There was a little heap of bones lying die out here on Mars is to in an agony of fatigue. give up." I reached over and turned up the pressure on her all my fault, too. Val's usually oxymask to make things a little easier for her. Through And she probably thought flying bother. It was beyond her to see that some grease monkey back at the Dome was at fault—whoever the failure of the sandcat was it was who had failed to fasten down the engine of disappearances on the desert. sand in the delicate mechanism of the atomic engine. But no she blamed it all on me somehow: So we were out "Can't we turn back now, Ron?" Val pleaded. "Maybe there isn't any uranium in this sector at all. I think we're crazy to keep on searching at the time of the atomic wars. I heard Val sob, "He's a When Val's tired and overwrought arguing with her. I stared ahead at the bleak, desolate wastes of the Martian Val. "The surest way to But I'm determined to drive "Just pick us off in the desert?" "Try to keep going, Val." He gestured through the her. We had wandered fruitlessly over the red sands all gleaming, deadly blaster in his hand. We stared in horror. It was day, both of us listening for the glassite of the mask, I on the infinitely safer desert. tire, and I knew it must have been really rough on Val with her lovely but unrugged legs. could see her face contorted snapped. "Well, let me show you. You're on Mars hunting uranium, right? To mine and ship the radioactives back to Earth to keep the atomic engines going. Right?" point, because Val didn't lie unless she was so exhausted I nodded over at our geiger she didn't know what she was much inflamed by the idea of coming to Mars to help in the search for uranium as I was. We knew the pay was poor, but we had felt it a sort of everything. Now she was turning against me. I tried to jolly her. "Buck couldn't keep going. She was almost sleep-walking now. when it happened. I never got the contract, but I got a good dose of radiation instead. Not I started to feel tired myself, terribly tired. I longed enough to kill me," he said. spongy Martian sand and bury myself. I looked at Val. She was "Just enough to necessitate that sudden explosive tumult that meant we had found pay-dirt. dragging along with her eyes the Val who had so enthusiastically Dome, and swore to get even. There's not a great deal of uranium on this planet, but enough to keep me in a style to which, unfortunately, I'm moment she was fast asleep, but I squelched it: table and fumbled in a container "There are other injections, too. Adrenalin, insulin. I watched her, sleeping Others. The Blast turned down over one eyebrow, and the needle into his arm. My eyes widened. It was it seemed hard to believe that we'd exchanged Earth and all too nightmarish to be real. I then Val stirred and rolled over in her sleep, and I didn't I saw the horror on Val's face, and I knew she felt the Val's quick, worried head-shake The wind blasted a mass of sand into my face, and I felt it tinkle against the oxymask. I glanced at the suit-chronometer. Getting late. I decided once again to wake Val. But she was tired. And I was tired too, tired from our wearying journey across the I started to shake Val. But Uneasily I caught Val's her smooth forehead faster I awoke with a sudden startled than the auto-wiper could I had let myself doze off. "Come on, Val," I said savagely, swab it away. " I hissed to Val, low. She began immediately to cough violently, emitting harsh, choking sobs. "Can't breathe!" She began to yell, writhing in her bonds. That did it. Ledman hadn't much humanity left in him, Val, and saw that she was Earthman who had bound us. I rolled my eyes toward what was wrong with Val. She continued to retch and moan most horribly. It almost convinced me. I saw Val's to struggle futilely, and I had to snap, "Lie still, Val!" over. The blaster went off, burning a hole through the Dome roof. The automatic sealers glued-in instantly. Ledman went sprawling helplessly out wore an outmoded, bulky spacesuit and a fishbowl helmet, all but the face area opaque. The oxygen cannisters I rolled over and covered Val rolled over to me. spacesuit ended neatly at the thighs. He was holding in his left hours, complacently waiting painfully. Then anger ripped through He was groaning and Val rolled on the floor and her face lay near my right arm. I saw what she had in mind. She began to nibble the vile-tasting tangle-cord, running her teeth up and down it until it started to give. She side to MELT, and shot a stream of watery fluid over our legs, keeping the blaster trained on us all the while. flipped the little switch on its to make trouble." Val and I melted the remaining tangle-cord off. My muscles were stiff and bound against the sides of our oxysuits. wince. I turned and freed Val. I glimpsed the bulk of an outboard atomic rigging behind him, strapped to the Val asked in a low voice as we "I don't quite know, Val. everyone at the Dome." "Quiet up there!" our captor that you couldn't bear to hang around on Earth for as much The answer to that came to me quick enough: we had to. Earth needed radioactives, and the only way to get them was to get out and look. The great atomic wars of the late again. "They told me I was paralyzed below the waist. That I'd never walk again, I had no muscles to fit "You left Earth too quickly," protested. "I had to get off—" They had used their atomics to make bombs. We used ours for fuel. It was an atomic world. Everything: power drills, powered by the inexhaustible energy of the dividing atom. But though the energy is the supply failed. The mighty machine that was Earth's industry had started to slow to end up as a madman's prisoners, on Mars. With every source of uranium mined dry on Earth, we had tried other possibilities. All sorts of Sea-Dredge was trying to get uranium from the oceans. In forty or fifty years, they'd get some results, we hoped. of being holed up here legs. I might have walked They told me I'd never walk," in it in the useless shell of a great atomic civilization. So, Mars. There's not much uranium on Mars, and it's not easy to find or any cinch to mine. But what little is there, Enter the Geig Corps: volunteers out on the face of Mars, combing for its uranium deposits. gave Val the blaster and slipped And here we are, I thought. out of my oxysuit. "Look," I said. I pointed to my smooth, gleaming metal "Of course not," I said. I Val got him into his suit, and how tired Val had been out on the desert. I realized now that I had been driving her mercilessly—me, with my chromium legs and atomic-powered muscles. No wonder she was ready to fold! And I'd been too dense to see Val slipped her oxymask

<question>:
Why did Val become so tired during her trek across the desert?

<options>:
A She did not have the technology that enabled Ron to persist
B She became consumed with resentment for having traveled to Mars
C She had trouble adjusting to the Martian climate and terrain
D Uranium was seeping through her space suit

<answer>:

A