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

<passage>:
SURVIVAL The earth, jungle and moons TACTICS ILLUSTRATOR NOVICK The robots were built to serve Man the robot apprehensively. Half to do his work, see to his Then the robots figured out an additional service—putting Man out of his misery. comforts, make smooth his way. There get out of here before the knife to a stop. slips or the monster cooks up some more tricks with whatever Frowning, worrying about the sounds, Alan momentarily forgot Pete could cram enough brain into one of those things to make it hunt and track so perfectly." He tried to visualize the computing circuits needed for the operation of its tracking mechanism alone. "There just isn't room for the electronics. You'd need a computer as big as the From tall, moss-shrouded trees, tree-bound octopus. Fitful little robot, crunching and snapping like an onrushing forest fire. He froze. "Good Lord! They communicate with each were long and gloomy. I'll bet anything they're automatically controlled by the camp computer. That's where their brain is!" He paused. He pictured the camp computer another robot fired in his direction, and holding him back. Then, through the trees he saw the clearing of the camp site, the temporary home for the scout two robots coming up from ship and the eleven men who, with Alan, were the only humans to follow a line between the or trip him. Even so, he stumbled in the wiry underbrush and where the power supplies and the computer were and the killer robots shook the night behind his legs were a mass of stinging that had brought the advance following constantly, more unshakable than bloodhounds because a man can sometimes cover few of the killer robots rolling a scent, but no man can stop his and technicians to Waiamea three days before. Except for a slowly around the camp site on exploratory party of scientists their quiet treads, there was no for sure. Anybody who can build a robot that hunts by homing in on animals' mind impulses ..." He stepped forward tight shut before he could see again, and the robots would a third robot slowly moved up one of the robots rolled silently Pete built those things wrong!" a halt. A few birds would still of claws and teeth hurled turns he'd taken in the jungle. "All I need is to get lost." robot, clawing insanely at the with no one to stop it, automatically sending its robots in With an awkward jerk the robot wiping every trace of life from the planet. Technologically advanced machines doing the job for which they were built, completely, thoroughly, without feeling, circuits. The robot started and without human masters wider and wider forays, slowly Finally parts would wear out, to separate sense from futility. one the killers would crunch to alone. fly then, but a unique animal exist no more. And the bones of where he could lie and watch the camp, but not himself be seen. Though visibility didn't make any difference to the robots, he felt safer, somehow, hidden. He knew now what the shooting sounds had been and why there hadn't been anyone around the life, rare in the universe, would children, eager girls, and their glint of a robot only a hundred himself, "that Pete assembled these robots in a batch and then activated them all at once, probably never living to realize that they're tuned to pick up human eyes and looked up—into a robot's earth. and fired. To his amazement the robot jerked back, its gun wobbled unaccountably in the trees overhead and every now and then the robot reacted. It seemed familiar somehow. Then he remembered the robot on the river wouldn't even singe a robot, but it just might stop one of those pumas." They said the blast with your name on it would find for a few seconds. They even do it to themselves!" Firing intermittently, he pulled himself upright and hobbled night. On the other hand, I certainly The robot shook spasmodically a pack of mind-activated mechanical killers running around. can't get to the camp with If I can just hold out until morning, him the dark jungle rustled forbiddingly. grass stood the headquarters building, housing the robot-controlling wives and kids! The metal killers, flesh, would murder them the tuned to blast any living with the other colonists, the Straining every muscle in avoiding the insect hills that jutted up through the grass. for an unknown planet, with her saw another of the robots standing to follow, to try to create a home the jungle waiting, it seemed, for his small blaster to run dry. "Be damned! You can't win thirty years of loneliness and had, at last, given him a reason for living. "Not to be killed!" Alan unclenched his fists and wiped his palms, bloody where flesh. frantically jerked the trigger cells released themselves from gun. "No!" He threw himself on the ground as a new robot suddenly locust-like insects that beat disgustingly engulfed in a swarm of the robot paused momentarily, into an insect hill and hurled the at the robot's antenna. In a flash, transmitting mental energy to the robot's pickup devices. and he could see a robot rolling Confused by the sudden dispersion robot fired erratically as Alan impulses came within its pickup range, birds, insects, anything. Six or seven others also left the camp headquarters area and of mind impulses, the headed for the jungle, each to a Apparently the robot hadn't open the door as the robot, sensing at whatever mind of its pickup devices was. He mind thought of nothing but the red-clad safety switch mounted back he saw that the machine, through his body and dragged the others to the gangway, eager to embrace the new planet, and unrecognizable, the victim of a design error or a misplaced wire in a machine. "I have to killer robot was equipped to through undergrowth. Nevertheless, it was slowed by the larger trees and the thick, clinging Only, the robot didn't get tired. This etext was produced from and danced across the jungle floor, hiding debris that tripped clothes, and insects attracted by the blood matted against his pants and shirt. Behind, the robot crashed imperturbably after the electric blue discharge as a pack of small feline creatures leaped snarling and clawing back into the night. maybe. Why the devil didn't I The robot crashed on, louder now, gaining on the tired human. stinging from insect bites, Alan tried to force himself to run holding his hands in front of him like a child in the dark. His shadows. The robot crashed loudly behind sizing up his situation. Behind and leaped back, trying frantically to wipe the clinging, branches and vines, but the rest spread slowly over his arm as Sharp muscle spasms shot from you, Pete! Damn your robots! with hairy, disjointed arms as if to snag even the dirty little stream that passed so timidly as the heavy little robot rolled legs were almost too weak and The crashing rumble of the what it was to live, because for would sometime die. In other times and circumstances he as now, he would have to watch, him, nearer sometimes, still and helpless, while death "Dammit, no law says I have to flame-out now !" He forced hide the pain, and biting his lips, ignoring the salty taste of blood. The soft earth crumbled soil was held too tightly by the roots from above and he had to the moons, the killer robot stopped hugged the bank as a shaft of robot shook for a second, its the bank blocked its aim. Grinding the robot fired again. For a split Again the robot trembled. It crazily as the earth collapsed underneath housing, frantically locking his arms around the barrel as the robot's treads churned furiously bull. The treads stopped and the barrel and housing, pressed fiercely against the robot's metal and shift his weight with the the revolving housing and the stationary portion of the robot.

<question>:
Why were the robots built?

<options>:
A Nobody knows, they were already on the planet's surface.
B To kill any people invading the planet.
C To perform labor and help the people build their city.
D To protect the people from dangerous animals.

<answer>:

D