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

<passage>:
It was alien but was it dead, this towering, sinister city of metal that glittered malignantly before the An hour later they surfaced about two hundred yards away from the edge of the city. Behind them the black pile rose, the dome of force toward the surface. "Come on, Rodney. Last lap." standing by the scoutships, and at the edge of the city, began to run at the city a quarter-mile away. He saw the dull, black walls of buildings shouldering grimly into the landed, the too-strict geometry imposed on the entire construction. He frowned. The first impression was ... malignant. a graceful movement of hand and arm he indicated the waiting city. sky, and harsh and black against it, the convoluted earth. And the city. Malignant. He wondered, again, what beings would choose to build a city—even a city like this one—in such surroundings. geometric discovery. Theirs was the eleventh inter-planetary flight, and the previous ten, in the time allowed them for exploration while this planet was still close enough to their own to permit a safe return in their ships, had not spotted the city. But the eleventh expedition flight could be safely started. So far as was known, this was the only city on the planet—the planet without any life at all, save tiny mosses, for a million years or more. And no matter which direction from the city a man moved, he would always be going north. of. I wonder what they were like?" Three feet from the edge of the city Martin stopped and stubbed at the Martin shrugged. "Clear around the city? I'd like to know what it is—was—for." surrounded by the tallest buildings in the city. Wass looked at him shrewdly. "Neither were the—well, shall we call Then—"I wonder what it's like here in the winter when there's no light at all?" "If we don't hurry up and get through this place and back to the ship, we're very likely to find out." Rodney said quickly, "I mean outside." lay ... and he thought everything outside the city seemed, somehow, He straightened his shoulders. The city was alien, of course, and that explained most of it ... most of it. But he felt the black city was something familiar, yet twisted and distorted. What's the matter, Wass?" There was a pause. Then Wass, defensively—"It's almost as if the city along this street." heavier gravity, remembered the inhabitants of the city vanished before it's like a glass wall." "We're trapped, we're trapped, they are—" "Shut up, Rodney! Wass, I'm only two sections from the edge. I'll check here." "No go," Martin said to Wass. He bit at his lower lip. "I think it must be all around us." He was silent for a time, exploring the consequences of this. Then—"We'll meet you in the middle of the city, where we separated." this?" He shook his head angrily, saying, "Judging by reports of the rest of the planet, it must have been horribly radioactive at one time. All of Wass said coldly, "He's right, Martin." Martin crossed an intersection, Rodney slightly behind him. "You're both wrong," he said. "We landed here today." Rodney stopped in the middle of the metal street and stared down at They reached the center of the city, ahead of the small, slight Wass, "The shield?" cover the city." "I wonder where it gets its power?" "Down below, probably. If there is a down below." Martin hesitated. "We may have to...." "What?" Rodney prompted. the streets. There were a multitude of doors and arches set into Martin chose an arch, with beyond it a metal ramp, which tilted downward, gleaming in the pale circle of his torch. A call from Rodney halted him. "Back here," the tall man repeated. "It looks like a switchboard." come to associate with the city builders. The three torches, shining "Is this it," Wass murmured, "or an auxiliary?" Martin shrugged. "The whole city's no more than a machine, apparently." "The ship leaves in eleven hours." stand!" Wass moved silently through the darkness beyond the torches. "We all the city would take years." Martin nodded. "But there must be central roads beneath this main level the dome, does it project down into the ground as well?" "You mean dig to themselves." "Anyway," Martin decided, "we can take a look down below." "In the pitch dark," Wass added. a circle. "No supports. No supports anywhere. What keeps all that up there?" "No, no," Martin answered impatiently, "not just here. I mean the whole city." "Yes," Wass said dryly, "it does. I'm sure this is where all my The edge of the city—the city which was a dome of force above and a Martin was in the lead. Wass followed him silently. Rodney, tall, sighed. He remembered how the dark buildings of the city looked at surface level, how the city itself looked when they were landing, and But—The only city, so far as anyone knew, on the first planet they'd Martin thought perhaps the city was built by a race of beings who at metal, which was making him theorize so wildly. Light from their torches was reflected, as from glass. "All right," Rodney said belligerently into his radio. "What's holding Martin thought of the dark, convoluted land outside the city. If they water." Rodney came last up the ramp, less jaunty now, but still holding the little moisture in the atmosphere." They stood before the switchboard again. Martin and Wass side by side, Postpone and postpone until it's too late, and the ship leaves without us and we're stranded here to eat seeds and gradually dehydrate ourselves and God only knows what else and—" He reached out convulsively and yanked a switch. resort. We still have a little time." "Water," Wass said thoughtfully. "There must be reservoirs under this city somewhere." Martin placed one foot on the metal incline. He angled his torch down, picking out shadowy, geometrical shapes, duplicates of the ones on the present level. "We'll find out," he said, "how many there are." think it's the last." They walked down the ramp and stood together, silent in a dim pool of artificial light on the bottom level of the alien city. Wass agreed. "And the survivors retired here. Why?" it off, Wass. We're looking for reservoirs, you know." "... The reservoirs, Wass. The pattern will still be here for later Right here." the same metal as everything else in the city, set beside the disk. From its design Martin assumed that the disk was meant to be grasped and turned. He wondered what precisely they were standing over. "Well, Skipper, are you going to do the honors?" hinge. The three men, clad in their suits and helmets, grouped around the six-foot opening, shining their torches down into the thing that drifted and eddied directly beneath them. The hatch rose again at Martin's direction. He stood beside it, outlined in the light of two torches. Then—causing a gasp from Wass, a harsh expletive from Rodney—a tenuous, questing alien limb edged through the hatch, curling about Martin, sparkling in ten thousand separate particles in the torchlight, obscuring the dimly seen backdrop of geometrical processions of strange now, himself. "How deep," Wass said, from his safe distance. Rodney, all eagerness to be of assistance now, lowered a rope with a torch swinging wildly on the end of it. The torch came to rest about thirty feet down. It shone on gently He sighted a path parallel with the avenue above, toward the nearest edge of the city. "I think we'll be all right," he called out, "as long as we avoid the drifts." sank into the dust. "Not me," the answer came back quickly. "You two fools go your way, I'll go mine." "Wass!"

<question>:
Where was the city located?

<options>:
A At the equator
B The location is not disclosed
C At the north pole
D At the south pole

<answer>:

D