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

<passage>:
QUEST OF THIG to subdue a defenseless world—only to meet on Earth emotions that were more deadly than weapons. Thig carefully smoothed the dark sand and seaweed of the lonely beach Lewis Terry was going fishing. For a week the typewriter mill that had shiny-buttoned bane of the typist, but there were no results. Feebly "He resembles Thig," announced Kam. "But for the strange covering he wears he might be Thig." "Thig will be this creature!" announced Torp. "With a psychic relay we will transfer the Earthman's memories and meager store of knowledge to the brain of Thig! He can then go out and scout this world without arousing suspicion. While he is gone, I will take Kam and explore the two inner planets." these clumsy sheathing upon his body. On Ortha we do not hamper the use of our limbs so." "Do not question the word of your commander," growled Torp, swelling out his thick chest menacingly. "It is for the good of our people that "For the good of the Horde," Thig intoned almost piously as he lifted Terry's body and headed for the laboratory. body and kept the electrical impulses throbbing from his tortured brain, but after the third suspension of life Thig removed his helmet. "There is nothing more to learn," he informed his impassive comrades. that episode gave Thig an idea about the little lump of jewels in his "Sorry I was late," he said, digging into his pocket for the Thig tried to tell himself that it was the transmitted thoughts of the of Ellen and the man he had destroyed. Thig groaned. He was a weakling to let sentimentality so get the better of his judgment. He would go now to the space ship and urge them to blast off for Ortha. He sprang off the porch and strode away down the "You have done well," announced Torp when Thig had completed his report "I will recommend the conquest of this planet, 72-P-3 at once and the complete destruction of all biped life upon it. The mental aberrations "Only the good of the Horde matters!" shouted Torp angrily. "Shall a race of feeble-witted beasts, such as these Earthmen, stand in the way of a superior race? We want their world, and so we will take it. The There are forces at work upon Earth that we of Ortha have long forgotten." "Check the blood of Thig for disease, Kam," ordered Torp shortly. "His words are highly irrational. Some form of fever perhaps native to this world. While you examine him I will blast off for Ortha." squat scientist's desk. His eyes roamed over the familiar instruments broad fingers bit deep into the unyielding metal of his chair. Suddenly he knew that he must go back to Earth, back to Ellen and the children of the man he had helped destroy. He loved Ellen, and nothing must empty world—this planet was not for them. "Turn back!" he cried wildly. "I must go back to Earth. There is a woman there, helpless and alone, who needs me! The Horde does not need this planet." Kam eyed him coldly and lifted a shining hypodermic syringe from its case. He approached Thig warily, aware that disease often made a maniac of the finest members of the Horde. Kam's startled throat and choked off any cry for assistance before it could be uttered. Kam's hand swept down to the holster swung from his intricate harness and dragged his blaster from it. Thig's other hand clamped over his and for long moments they swayed there, locked together in silent deadly struggle. The fate of a world hung in the balance as Kam's other hand fought against that lone arm of Thig. The scales swung in favor of Kam. Slowly the flaring snout of his suddenly released his grip and dragged his enemy toward him. A sudden reversal of pressure on Kam's gun hand sent the weapon swivelling about full upon its owner's thick torso. Thig's fingers pressed down Before Thig's eyes half of his comrade's body sloughed away into foul corruption that swiftly gave way to hardened blobs of dessicated matter. Horror for what he had done—that he had slain one of his own Horde—made his limbs move woodenly. All of his thoughts were dulled for the moment. Painfully slow, he turned his body around toward the His body seemed paralyzed. This was the end, he thought as he waited stupidly for the blow to fall, the end for Ellen and the kids and all was in the corner of the laboratory, a crumpled blood-smeared heap of bruised flesh and bone. He was unfettered and the blood was caked upon his skull and in his matted hair. Torp must have thought he had killed him with those savage blows upon the head. Even Torp, thought Thig ruefully, gave way to the primitive rage of his ancestors at times but to that very bit of unconscious atavism he now unconscious body. Thig rolled slowly over so that his eye found the door into the control room. Torp would be coming back again to dispose of their bodies through the refuse lock. Already the body of Kam was gone. He wondered why he had been left until last. Perhaps Torp wished to take cultures of his blood and tissues to determine whether a disease was responsible for his sudden madness. In a moment he was on his knees crawling across the plates of the deck toward the door. Halfway across the floor he collapsed on his face, the metal of the gun making a harsh clang. He heard the feet of Torp scuffle out of silence and a choked cry in the man's throat squalled full into the glaring vacant orbs of his commander. Torp leaned there The deadly attack of Thig his own violent avenging of Kam's death, and now the apparent return of the man he had killed come to life had all served to jolt his rigidly trained brain from its accustomed groove. The shock had been too much for the established thought-processes of the Orthan. the skeleton-thing that had been Torp, using the new strength that victory had given him to drive him along. He had saved a world's civilization from extinction! The thought sobered him yet, somehow, he was pleased that he had done so. After all, it had been the Earthwoman and the children he had been thinking of while he battled Kam, a selfish desire to protect them all. He went to the desk where Torp had been writing in the ship's log and read the last few nervously scrawled lines: strikes at the brain centers and causes violent insanity is existent there. Thig, just returned from a survey of the planet, went mad and destroyed Kam. In turn I was forced to slay him. But it is not ended. Already I feel the insidious virus of.... And there his writing ended abruptly. path she would return safely to Ortha with that mute warning of danger on 72-P-3. The body of Torp would help to confirm his final message. Then Thig crossed the cabin to the auxiliary life boat there, one of regret in his mind that he was not returning to the planet of his first existence. He shivered suddenly, remembering his utter callousness the first time he had sent a space ship whipping down toward the hills and valleys below. And there was a sickness within him when he fully realized that, a brief prayer in his heart to a God whose presence he now felt very deeply. There were tears in the depths of his eyes, then, and memories were hot, bitter pains. now, for the rest of his life, he must make up to the dead man's family. The knowledge that Ellen's love was not really meant for him would be a knife twisting in his heart but for her sake he must endure it. Her

<question>:
Why does Thig leave a note at Torp's desk?

<options>:
A He wants to make sure no one comes to invade Earth, and have reason to fear doing so.
B He wants to warn the other Orthans about the potential dangers of Earth.
C He wants someone to understand what had happened.
D He feels badly about killing Kam and Torp, and wants to leave a final message on their behalf.

<answer>:

A