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

<passage>:
Never had Mars seen such men as these, for they came from black space, carrying weird weapons—to fight for a race of which they had never heard. Ro moved cautiously. He knew the jungles of Mars well, knew the And, most of all, he wanted to see Na, graceful, dark eyed Na, whose He breathed a sigh of relief as he reached the jungle's edge. Before The sun beat down on his bare head and back. His red skin glistened. His thick black hair shone healthily. Mile after mile fell behind him. His long, well muscled legs carried in surprise. The pursued was a young woman, a woman he knew. Na! The on his prey to notice Ro at first, and when he did, it was too late. fear of one who sees approaching death was in his movements and his cry. He had seen many Oan die because of the strength and accuracy in the red men's arms. With hardly a glance at his fallen foe, Ro ran on to meet the girl. She Finally Na lifted her beautiful head. She looked timidly at Ro, her Na lowered her eyes. "I was caught in the forest below the cliffs. The Oan spied me and I "You were alone in the woods!" Ro exclaimed. "Since when do the women "The men of our tribe snatched up stones, and holding one in their hands and one beneath their armpits, they climbed down to battle or "They were strange men indeed white as the foam on water, and clothed in strange garb from the neck down, even to coverings on their feet. They made signs of peace—with one hand only, for they carried weapons of a sort in the other. And the men of our tribe made the same one-handed sign of peace, for they would not risk dropping their stones. Then the white men spoke but their tongue was strange, and our men signaled that they could not understand. The white men smiled, and a great miracle took place. Suddenly to our minds came pictures and words. The white men spoke with their thoughts. "They came from a place called Earth, they said. And they came in peace. Our men found they could think very hard and answer back with woman with golden hair, and the other, a man of age, with hair like silver frost. "There was a great feast then, and our men showed their skill at throwing. Then the white men displayed the power of their strange weapons by pointing them at a tree and causing flame to leap forth to burn the wood in two. We were indeed glad they came in peace. "That night we asked them to sleep with us in the caves, but they made camp in the valley instead. The darkness passed swiftly and silently, and with the dawn we left our caves to rejoin our new friends. But everywhere a red man showed himself, he cried out and died by the flame from the white men's weapons. "I looked into the valley and saw hundreds of Oan. They had captured our friends in the night and were using their weapons to attack us. cover of night, we were forced to leave the caves. One by one we went, and those of us who lived still travel alone." Ro groaned aloud as Na finished her tale. His homecoming was a meeting Na trailed behind him. Her face was grave with concern. "They are very many," she said. "Then there will be more to kill," answered Ro without turning. "They have the weapons of the white ones." "And the white ones, as well. They probably keep them alive to repair the weapons if they become useless. But when I have slain a few Oan, I will set the white ones free. They will help me to make more weapons. Together we will fight the rat men." Na smiled. Ro was angry, but anger did not make him blind. He would another clearing, he could see many Oan, flitting ghost-like from place There were no fires, for the Oan were more beast than man and feared Ro was silent then. In a short time it would be dark enough to go down He turned away from the valley to study Na. She was very beautiful. The darkness settled quickly. Soon Ro could barely make out the girl's clasped on Na's wrist. Without another word he disappeared over the edge of the cliff. They The climb was long and dangerous. Ro's skin glistened with sweat. He had lived in the cliffs all his life, and had made many perilous Feeling his way cautiously, he moved toward the camp. He could sense the night. Ro could see his large ears, hear his twitching tail. In a clearing without making a sound. Strewn on the ground were shapeless easily as each came free and he started on the next. When they were ready, Ro signaled the four white people to follow him. They rose quietly and trailed him into the woods. The girl whispered them and Oan camp grew. Ro increased his pace when silence was no told them. "After a short while, we will meet Na." "Who is Na?" asked the girl. The white girl was silent. They traveled quite a distance without communicating. Each was busy with his own thoughts. Finally the man with the silver hair asked, "Why did you risk your life to rescue us?" "With your help I will avenge the death of my father and brothers and the men of my tribe." He stopped walking and stared around him for a landmark. They had traveled far along the foot of the cliff. According to the plan Na Na was just opening her eyes. She stared around her fearfully, then Na turned her head and saw the body of the rat man. She shuddered. standing at the foot. The shadows were deceiving. I thought it was you. When she had recovered from her shock, the small group traveled on. Ro "We will stay here," he told the others, "until we are ready to attack the Oan." "But there are only six of us," one of the white men protested. "There are hundreds of the beasts. We wouldn't have a chance." Ro smiled. He sat in a corner of the cave and leaned back against the wall. His the white ones. The man with the silver hair seemed very old and weak, but very wise. The other men had hair as black as any Martian's, but their skin was pure white. They were handsome, Ro thought, in a barbaric sort of way. One was lean and determined, the other, equally determined, but stouter Ro introduced himself and Na. Ro slipped his arm about Na's shoulder and drew her closer. With their Ro awakened with the dawn. He was startled to find that Na had left his Na met him at the entrance. She was returning from a clump of trees The others in the cave awakened. Ro noticed that Charlotte had slept beside Carlson, but moved away shyly now that it was daylight. He When they had finished breakfast, they sat around the floor of the cave "The Oan are cowards," Ro answered. "They are brave only because they twisted in anger. "You're lying," he shouted aloud, forgetting that the white man couldn't understand his words. "You're lying because you are afraid. You refuse to help me avenge my people because you are more of a coward Ro fell silent. He walked to the mouth of the cave and stared out. When he turned back to the others, his attention was centered on Na. camp. All of the rat men cannot be guarding it. Perhaps, by revealing "She will be a woman alone," said Ro. "The Oan prefer to capture women "Do you think I will let her go alone? I will be close by. Na can lead "Why me?" Grimm demanded. "Why not Carlson? Or are you saving him for swiftly. He caught the white man and forced him back. "This is no time for fighting," he said. "When the Oan are defeated you can kill each other. But not until then." "I'll go with you," he said. "Grimm can go with Charlotte and the When they had detailed their plan, the party left the cave. Ro led them "We leave you here," said Ro to the professor. "Na will lead you to the Ro looked at Na for a long moment before they parted. He grew very Once Ro stopped to look down into the valley. But Na and the others he said, "I didn't want to make trouble. It was a bad time, and Ro didn't speak. He didn't concentrate and transmit his thoughts,

<question>:
Why was Na alone in the forest?

<options>:
A Because strange men landed in a metal sphere
B Because Ro had traveled far to the north
C Because the rat men killed most of their people
D Because the white men carried weapons

<answer>:

C