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

<passage>:
was the last thing Martin heard before he collapsed. cavorting in the distance, moving toward them. He grinned a little, adjusting his radio. "Worried?" Rodney's bony face was without expression. "Gives me the creeps, kind of. I wonder what they were like?" Rodney's laughter rose, too. Then, sobering—"Maybe they crawled." A nebulous image, product of childhood's vivid imagination, moved slowly across Martin's mind. "All right!" he rapped out—and the image faded. "Sorry," Rodney murmured, his throat working beneath his lantern jaw. Martin ignored the remark. "Go get it. Rodney and I will be somewhere along this street." decided to grin at himself, at his own imagination. Rodney jerked his scarecrow length about quickly, and a chill sped up Martin's spine. "What's the matter?" The bony face was white, the gray eyes were wide. "I saw—I thought I Rodney stared. "The wind. Remember? There isn't any, here." "... How could there be? The buildings protect us now. It was blowing from the other direction." Rodney wrenched free of Martin's grip. He gestured wildly. "That—" "Martin!" Wass' voice came through the receivers in both their radios. "Martin, I can't get out!" Rodney mumbled something, and Martin told him to shut up. Wass said, more quietly, "Remember that metal band? It's all clear now, and glittering, as far as I can see. I can't get across it separated." Walking with Rodney, Martin heard Wass' voice, flat and metallic Rodney interrupted, "There hasn't been enough radiation around here for hundreds of thousands of years to activate such a screen." Wass said coldly, "He's right, Martin." Rodney stopped in the middle of the metal street and stared down at Martin. "The wind—?" "Why not?" "That would explain why it stopped so suddenly, then." Rodney stood straighter. When he walked again, his steps were firmer. may have to...." "What?" Rodney prompted. A call from Rodney halted him. "Back here," the tall man repeated. "It looks like a switchboard." Rodney furtively, extended one hand toward a switch. "No!" Martin said, sharply. That was one assumption they dared not make. Rodney turned. "But—" "No. Wass, how much time have we?" He directed his flashlight at Rodney's thin, pale face. "What do you think you're doing?" Rodney cursed. "And every second we stand here doing nothing gives us that much less time to find a way out. Martin—" After a moment, Wass switched his flashlight back on. He said quietly, "He's right, Rodney. It would be sure death to monkey around in here." Martin hung back waiting for the others to go ahead of him down the Rodney's gulp was clearly audible through the radio receivers. "Here?" "No, no," Martin answered impatiently, "not just here. I mean the whole city." "We go back, I guess," Martin said. Rodney turned swiftly to face him. Martin thought the tall man was holding his gun. "To the switchboard, Martin?" "Unless someone has a better idea," Martin conceded. He waited. But Rodney was holding the gun ... and Wass was.... Then—"I can't think of anything else." Martin was in the lead. Wass followed him silently. Rodney, tall, matchstick thin, even in his cumbersome suit, swayed with jaunty triumph in the rear. "All right," Rodney said belligerently into his radio. "What's holding up the procession?" Martin was silent. Wass undertook to explain. Why not, after all? Martin asked himself. It Rodney came last up the ramp, less jaunty now, but still holding the gun. His mind, too, was taken up with childhood's imaginings. "For Rodney, still holding his gun, slightly to the rear. Rodney moved forward a little toward the switches. His breathing was loud and rather uneven in the radio receivers. Rodney jerked his head negatively. "No. Now, I know you, Martin. Postpone and postpone until it's too late, and the ship leaves without ourselves and God only knows what else and—" He reached out convulsively and yanked a switch. Martin leaped, knocking him to the floor. Rodney's gun skittered away silently, like a live thing, out of the range of the torches. The radio receivers impersonally recorded the grating sounds of Rodney's sobs. "Sorry," Martin said, without feeling. He turned quickly. "Wass?" The slight, blond man stood unmoving. "I'm with you, Martin, but, as Martin was watching Rodney, struggling to get up. "I agree. As a last resort. We still have a little time." Rodney's tall, spare figure looked bowed and tired in the torchlight, now that he was up again. "Martin, I—" Martin turned his back. "Skip it, Rodney," he said gently. the floor. "Martin, what if there are no reservoirs? What if there are cemeteries instead? Or cold storage units? Maybe the switch I pulled—" "Rodney! Stop it!" Rodney swallowed audibly. "This place scares me...." "They had a war," Martin said. "In a minute," Martin said, too irritably, "we'll have a sentient planet." From the corner of his eye he saw Rodney start at that. "Knock "... The reservoirs, Wass. The pattern will still be here for later expeditions to study. So will we if we don't find a way to get out." Their radios recorded Rodney's gasp. Then—"Martin! Martin! I think I've found something!" Martin began to run. After a moment's hesitation, Wass swung in behind him. "Here," Rodney said, as they came up to him, out of breath. "Here. See? Right here." Rodney's sudden grip on Martin's wrist nearly shattered the bone. "Martin! It's all alive! It's moving!" He was shaking. After a time he said, "Rodney, Wass, it's dust, down there. Remember the wind? Air currents are moving it." Rodney sat down on the metal flooring. For a long time he said nothing. Then—"It wasn't.... Why did you close the hatch then?" Martin did not say he thought the other two would have shot him, otherwise. He said merely, "At first I wasn't sure myself." Rodney stood up, backing away from the closed hatch. He held his gun Martin went to the wheel. He noticed Wass was standing behind Rodney and he, too, had drawn his gun. outlined in the light of two torches. For a little while he was alone. Then—causing a gasp from Wass, a harsh expletive from Rodney—a Rodney leaned forward and looked over the edge of the hatch. He said nothing. He eyed the sparkling particles swirling about Martin, and now, himself. "All right, Wass," Martin said quietly, as Rodney released the rope and sank into the dust. "Not me," the answer came back quickly. "You two fools go your way, Martin pulled his left foot from the sand and growled deep in his Rodney stared. "Wass!" he shouted. "We've found a way out!" Their radios recorded Wass' laughter. "I'm at the switchboard now, Martin. I—" Martin switched off his radio, sick. "Well?" "I've been trying to get you," Rodney said, frantically. "Why didn't you answer?" "We couldn't do anything for him." Rodney's face was white and drawn. "But he did this for us." "So he did," Martin said, very quietly. Rodney said nothing. Then Martin said, "Did you listen until the end?" Rodney nodded, jerkily. "He pulled three more switches. I couldn't

<question>:
Why did Martin feel sick when they were able to escape?

<options>:
A He knew Wass had sacrificed his life
B The black city disturbed him
C He had to crawl for an hour through a pipe
D He saw Rodney was upset

<answer>:

A