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

<passage>:
easy, as the loping of Shee, the great cat. on his prey to notice Ro at first, and when he did, it was too late. "You were alone in the woods!" Ro exclaimed. "Since when do the women "That night we asked them to sleep with us in the caves, but they made Ro groaned aloud as Na finished her tale. His homecoming was a meeting Na trailed behind him. Her face was grave with concern. "And the white ones, as well. They probably keep them alive to repair Together we will fight the rat men." Na smiled. Ro was angry, but anger did not make him blind. He would make a good mate. understood why she had crept into his dreams. clasped on Na's wrist. "All men will know now that you are the mate of Ro," he whispered. And he kissed her, as was the custom of his tribe when a man took a wife. Without another word he disappeared over the edge of the cliff. They had already made plans for their next meeting. There was no need for a he rested at the bottom. Feeling his way cautiously, he moved toward the camp. He could sense prickled. He prayed he wouldn't be seen. An alarm now would spoil his the night. Ro could see his large ears, hear his twitching tail. In a moment the beast would stumble over him. Like a phantom, Ro arose from his crouch. The rat man was startled, heaps. They would be the slumbering rat men. Ro suppressed an urge to He lay flat on his stomach and inched his way ahead. It was slow work, feigned sleep. In the dusk he appeared no different than the others. was as though he was feeling hide that bound her wrists. He fumbled impatiently with the heavy knots. "Don't move when you are free," he warned the girl as he worked. "I Ro was more confident as he moved to untie the others. He worked more something to one of the men. Ro turned and glared at her through the Ro's body tensed and quivered. A low growl issued from deep in his Ro struck his foe head on. They went down in a frenzied bundle of fury. The rat man's tail lashed out to twist around Ro's neck. With frantic strength, Ro tore it away before it could tighten. thoughts. "Now we must rest." eyes were half shut and he pretended to doze. Actually he was studying pure white. They were handsome, Ro thought, in a barbaric sort of way. One was lean and determined, the other, equally determined, but stouter the lean man nodded—"Grimm—" the stouter man acknowledged the Ro sighed. would like to learn more, but we must sleep now. Tomorrow will be a very busy day." Ro slipped his arm about Na's shoulder and drew her closer. With their heads together they slept. Ro awakened with the dawn. He was startled to find that Na had left his well provided for." "You will make no mate at all," Ro said sternly, "and there will be no He glared at her for a moment, then smiled and helped her with her burden. The others in the cave awakened. Ro noticed that Charlotte had slept beside Carlson, but moved away shyly now that it was daylight. He noticed, too, that Grimm was seeing the same thing and seemed annoyed. Ro smiled. These young white men were no different than Martians where When they had finished breakfast, they sat around the floor of the cave and spoke. It was Carlson who asked, "How do you expect the six of us to attack the rat men?" Grimm laughed. Ro sprang to his feet to tower above the man. His handsome face was twisted in anger. couldn't understand his words. "You're lying because you are afraid. Grimm climbed to his feet and backed away. Ro advanced on him, his "He's lying," said Ro with his thoughts. "Tell him I'm speaking the truth, professor," said Grimm aloud. The professor repeated Grimm's words with his thoughts. "It would be "What is it?" he demanded. camp. All of the rat men cannot be guarding it. Perhaps, by revealing yourself, you can lure the guards away from their post." He repeated his plan to the others. "But they'll kill her," gasped Charlotte. "She will be a woman alone," said Ro. "The Oan prefer to capture women when they can." "Then she'll be captured," the professor said. "It's much too risky." Ro laughed. cliffs, waiting to pelt them with stones. Carlson or Grimm can be with be easy." The professor smacked his fist into his palm. "It might work at that. Grimm can go with you. Carlson and Charlotte will go with me." "Why me?" Grimm demanded. "Why not Carlson? Or are you saving him for your daughter?" Carlson grabbed Grimm by the shoulder and spun him around. He drove a hard fist into the stout man's face. Grimm stumbled backward. He fell at the cave's entrance. His hand, sprawled behind him to stop his fall, closed over a rock. He flung it at Carlson from a sitting position. It caught Carlson in the shoulder. Gritting his teeth, Carlson charged at Grimm. But Ro moved more swiftly. He caught the white man and forced him back. "This is no time for fighting," he said. "When the Oan are defeated you Grimm brushed himself off as he got to his feet "Okay," he sneered. "I'll go with the red man. But when we meet again, it will be a different story." Carlson turned to Ro. "I'll go with you," he said. "Grimm can go with Charlotte and the professor." proud of what he saw. There was no fear in her eyes. Her small chin was firm. He turned to Carlson. The young Earthman was looking at Charlotte in much the same way. "Come on," Ro said. "If we spend the rest of the morning here, the Oan will try some strategy of their own." Carlson seemed to come out of a trance. He swung around to trail Ro up the sloping part of the mountain. They climbed in silence. Once Ro stopped to look down into the valley. But Na and the others were gone. He felt a pang of regret as he turned to move upward. When they had reached the top, he and Carlson set to work piling rocks be trapped. They would die under a hailstorm of rock. "You would have liked a more tender goodbye with Charlotte," Ro said to Carlson as they worked. "Was it fear of Grimm that prevented it?" Carlson straightened. He weighed Ro's words before answering. Finally he said, "I didn't want to make trouble. It was a bad time, and senseless, besides. Charlotte and I are planning to be married when we return to America. It's not as though Grimm was still in the running. I'm sure he'll see reason when we tell him. It's foolish to be enemies." "Why don't you take her for your wife here on Mars? That would end the trouble completely." Carlson seemed surprised. "It wouldn't be legal. Who would perform the ceremony?" Ro seemed puzzled, then he laughed. can tell us whether it is 'legal' or not? What better ceremony than a kiss and a promise?" He bent back to his work chuckling. "I could argue the point," Carlson laughed. "I could tell you about a place called Hollywood. Marriage and divorce is bad enough there. Under your system, it would really be a mess. But I won't say anything. Here on Mars your kiss and a promise is probably as binding as any ceremony." Ro didn't speak. He didn't concentrate and transmit his thoughts, but kept them to himself. The pictures he'd received from Carlson were confusing. The business at hand was more grim and important than untangling the puzzle.

<question>:
Why is Grimm annoyed that Charlotte slept beside Carlson?

<options>:
A Because he is Charlotte's friend and he doesn't think that Carlson is good enough for her.
B Because he is Charlotte's father and does not approve of the relationship.
C Because he is the leader of the expedition and doesn't want his crew to get distracted with romance.
D Because he is in love with Charlotte and is jealous of the affection between her and Carlson.

<answer>:

D