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

<passage>:
Irgi was the last of his monster race, guardian of a dead planet, master of the secret of immortality. It was he whom the four men from Earth had to Irgi was the last of his race. There was no one else, now been no others for hundreds and hundreds of years. Irgi had lost count of time dwelling alone amid the marble halls of the eon-ancient city, Only Irgi, alone. clinging shelter, destroying dust and germs. Irgi had discovered the mist many years ago, when it was too late to save his kind. from the far-off jungle city of Kreed had he brought the riches of the Urg and set them up. Irgi enjoyed beauty, and he enjoyed work. It was In the doorway, Irgi paused and ran his eyes about the chamber, sighing. block possess. There was nothing they could not do, if Irgi so willed. Irgi moved across the room. He pressed glittering jewels inset in a Irgi drew himself upwards, slowly turning, laving in the quivering Irgi was immortal, and the blue light made him so. "I must speak," Irgi said as he moved along the corridor. "I have not will talk to them and tell them how lonely Irgi is." and the name and fame of Irgi means nothing to the walls of my city, nor to the Chamber of the Cones, nor even—at times—to Irgi himself." Emerson took his hands from the controls of the gigantic ship that "The last planet in our course," he breathed. "Maybe it has the radium!" "Yes," whispered the man beside him, wetting his lips with his tongue. "No use to think of failure. If it hasn't, we'll die ourselves, down there." Radium. And the Plague. It had come on Earth suddenly, had the Plague, back in the first days of space travel, after Quigg, the American research scientist at Cal Tech, discovered a way to lift a rocket ship off the Earth, and propel it to the Moon. beginning. And no one had thought anything of it when Quigg, who had made the first flight through space, died of cancer. As the years passed to a decade, and the ships of Earth rode to Mars and Venus, it began to be apparent that a lifetime of space travel meant a hideous death. Scientists attributed it to the cosmic rays, for out in space there was no blanketing layer of atmosphere to protect the fleshy tissues of man from their piercing power. It had long been a theory that cosmic rays were related to the birth of new life in the perhaps they were, said some, the direct cause of life. Thus by causing the unorderly growth of new cells that man called cancer, the cosmic rays were destroying the life they had created. It meant death to travel in space, and only the stupendous fees paid to the young men who believed in a short life and a merry one, kept the and an inner coating of lead brought men into port raving with lead poisoning illusions. Cancer cases increased on Earth. It was learned that the virulent form of space cancer, as it was called, was in some peculiar manner, contagious to a certain extent. The alarm spread. Men who voyaged in space were segregated, but the damage had been done. The Plague spread, and ravaged the peoples of three planets. Hospitals were set up, and precious radium used for the fight. But the radium was hard to come by. There was just not enough for the job. It had not been easy to find a crew. The three worlds knew the men were going to their doom. It would be a miracle if ever they reached a single planet, if they did not perish of space cancer before their first goal. Carson Nichols, whose wife and children were dying of the Plague, begged him for a chance. A murderer convicted to the Martian salt mines, Karl Mussdorf, grudgingly agreed to go along on the promise that he won a pardon if he ever came back. With Mussdorf went a little, "There it is, Karl," said Nichols. "Start hoping." Mussdorf scowled darkly, and spat. "A hell of a way to spend my last days," he growled. "I'm dying on my feet, and I've got to be a martyr to a billion people who don't know I'm alive." The ship rocked gently as Emerson set it down on a flat, rocky plain The spaceship settled down on the white flagging of an immense square. germs. No dust. Just clean air!" Emerson leaped to his side, staring, frowning. "No germs. No dust. Why—that means there's no disease in this place! No disease." He began to laugh, then caught himself. "No disease," he whispered, "and every one of us is going to die of cancer." Mussdorf came up through the trap and passed out the sun-blasters. They The big Earthman was lifted high into the air, squeezed until his lungs Irgi stared at the things that lay on the white flagging. Queer beings they were, unlike anything Irgi had ever conceived. Only two legs, only short work of them if an Urgian cat existed any more, and Irgi had Irgi bent to wrap long arms about the queer beings, lifting them. His legs, from face and chest. The growth disease! That was bad, but Irgi knew a way to cure it. Irgi knew a way to cure anything. He had been glad to find these creatures. They were someone to converse with after centuries of loneliness. But as he approached them ship. He had caught a confused, angry murmur on the radiation recorder. Perhaps the metal of the hull had in some manner made his voice audible electrigraph screen. That should be absorbing. It made Irgi happy, reflecting upon it, and Irgi had not known happiness for a long time. Irgi dropped his burdens. With quick tendrils he adjusted straps to "It's short-circulated their nervous systems for a while, absorbed the electric charges all intelligent beings cast," Irgi said aloud, glad at this chance to exercise his voice. "They won't be able to feel for some "I wonder if they've perfected this," Irgi mused. "They must be aware grew nebulous, then cleared. Irgi disease. Now he beheld the mighty salt mines where naked men swung huge picks at the crusted crystals, sweating and dying under a strange sun. Even these remnants of humanity festered with the growth. A tall, lean man in white looked out at him. His lips moved, and Irgi him with a spaceship, reciting the need of radium, the dread of the plague. The thoughts of this Emerson were coming in clearer, as Irgi in sudden interest, flipped over different dials. The unspoken thoughts pouring into his brain through the screen continued. The words he did Irgi stared upward at a colossal figure graven in lucent white marble. Irgi unfastened clamps, and rolled the screen aside. He reached to a Opening the laboratory door, Irgi passed out and closed it behind him. "That fiend," yelled Mussdorf. "That ten-eyed, octopus-legged, black-hearted spawn of a mismated monster did this to us. Damn him! Damn him! If I ever get loose I'll cut his heart out and make him eat it." "Maybe—maybe he's vivisecting us," moaned Nichols. "With rays or—or something—aagh! I can't stand it!" "You were our commander—out there, in space. We're on a planet now. Emerson squirmed helplessly, cursing him, saying, "What's gotten into

<question>:
How did Irgi come to be alone on his planet?

<options>:
A The text implies that the inhabitants of the planet Urg ruined their planet the way most intelligent races did - through the rages of nuclear war between nation-states.
B The text implies that a race of alien conquerors killed all of them except for Irgi.
C The text implies Irgi was a psychopath (in Earth terminology) who loosed a bioweapon on his own people, keeping the antidote only for himself, then regretted it later.
D The text implies that the same radiation sickness that is killing Terrans killed all of his people except him.

<answer>:

D