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

<passage>:
Grannie Annie, that waspish science-fiction writer, was in a jam again. What with red-spot fever, talking cockatoos and flagpole trees, Interstellar Voice three days ago, Earth time, and now as the immense disc of Jupiter flamed across the sky, entered the outer limits of the Baldric. Grannie Annie strode in the lead, her absurd long-skirted black dress looking as out of place in this desert as the trees. Flagpole trees. They rose straight up like enormous cat-tails, with only a melon-shaped protuberance at the top to show they were a form of vegetation. Everything else was blanketed by the sand and the powerful wind that blew from all quarters. As we reached the first of those trees, Grannie came to a halt. "This is the Baldric all right. If my calculations are right, we've hit it at its narrowest spot." Ezra Karn took a greasy pipe from his lips and spat. "It looks like the , and other works of science fiction. Blood-and-thunder as these books are, however, they have one redeeming feature—authenticity of background. "Glad to meet you," he said cordially. "I've just been trying to persuade Miss Flowers not to attempt a trip into the Baldric." "What's the Baldric?" I had asked. Antlers Park flicked the ash from his cheroot and shrugged. "Will you believe me, sir," he said, "when I tell you I've been out here at all is because of the presence of an ore known as Acoustix. It's no use to the people of Earth but of untold value on Mars. I'm not up on the scientific reasons, but it seems that life on the red planet has developed with a supersonic method of vocal communication. middle age, his ability to produce those vibrations steadily decreases. Then it was found that this ore, Acoustix, revitalized their sounding apparatus, and the rush was on." . Chap by the name of Jimmy Baker runs that. However, the point is, between the properties of these two companies stretches a band or belt which has become known as the Baldric. "There are two principal forms of life in the Baldric flagpole trees and a species of ornithoid resembling cockatoos. So far no one has crossed the Baldric without trouble." "What sort of trouble?" Grannie Annie had demanded. And when Antlers saw trouble yet that couldn't be explained. We leave in an hour." So now here we were at the outer reaches of the Baldric, four travelers on foot with only the barest necessities in the way of equipment and supplies. they suddenly faded like a negative exposed to light and disappeared. "What do you make of it?" I said in a hushed voice. Grannie shook her head. "Might be a form of mass hypnosis superinduced by some chemical radiations," she replied. "Whatever it is, we'd better watch our step. There's no telling what might lie ahead." We walked after that with taut nerves and watchful eyes, but we saw no repetition of the "mirage." The wind continued to blow ceaselessly, and the sand seemed to grow more and more powdery. For some time I had fixed my gaze on a dot in the sky which I supposed excellent living conditions with a vacation on Callisto every year. Up until a short time ago most of them were in excellent health and spirits. Then the Red Spot Fever got them." "Red Spot Fever?" Grannie looked at him curiously. Jimmy Baker nodded. "The first symptoms are a tendency to garrulousness on the part of the patient. Then they disappear." He paused to make an adjustment of the windlass. "They walk out into the Baldric," he continued, "and nothing can stop them. We tried following them, of course, but it was no go. As soon as they realize they're being followed, they stop. But the moment our eyes man's face formed in the vision plate. Baker listened, said "Okay" and threw off the switch. "The entire crew of Shaft Four have gone out into the Baldric," he said slowly. There was a large map hanging on the wall back of Baker's desk. Grannie Annie walked across to it and began to study its markings. "Shaft Four is at the outer edge of the Baldric at a point where that corridor is at its widest," she said. He flicked a stud, and the entire wall above the panel underwent a slow change of colors. Those colors whirled kaleidescopically, then coalesced into a three-dimensional scene. trouble up there. Red spot fever." "Fever, eh?" repeated Park. "That's a shame. Is there anything I can do?" "Tell me," I said, "has your company had any trouble with this plague?" "A little. But up until yesterday the fever's been confined to the other side of the Baldric. We had one partial case, but my chemists gave the chap an antitoxin that seems to have worked. Come to think of it, I might drive over to Shaft Four and give Jimmy Baker the formula. I haven't been out in the Baldric for years, but if you didn't have any trouble, I shouldn't either." We exchanged a few more pleasantries, and then he rang off. In exactly Then once more I was directly behind my friends, listening in on their conversation. The view through the windscreen showed an irregular array of copying speech, they also have the ability to recreate a mental image of what they have seen. In other words their brains form a powerful photographic impression of the object. That impression is then transmitted simultaneously in telepathic wavelengths to common foci. That eyrie might be likened to a cinema screen, receiving brain vibrations from a hundred different sources that blend into the light field to form what are apparently three-dimensional images." birds reconstruct images from the actual person. Why use drawings?" "Probably because the drawings are exaggerated in certain details and made a greater impression on their brains," Grannie replied. "That explains something at any rate," the old prospector said. "But how about that Red spot fever?" On Jimmy Baker's desk was a large file marked: FEVER VICTIMS. I opened part of the button appeared to be a powerful lens of some kind, and as I seized it and pulled it loose, I felt the hum of tiny clock work. All at once I had it! Red spot fever. Heat fever from the infra-red rays of Jupiter's great spot. Someone had constructed this lens to concentrate and amplify the power of those rays. The internal clockwork something screwy here." Ten minutes later in another kite car we were driving at a fast clip through the powdery sands of the Baldric. And before long we saw another car approaching. shattered our windscreen. The wind shifted and blew from another quarter. The box kite soared, but the triangular kite faltered. Taking advantage of Park's loss of had been removed, and mounted on the hood was a large bullet-like contrivance that looked not unlike a search lamp. A blinding shaft of bluish radiance spewed from its open end. Playing it back and forth "Ultra violet," Grannie Annie explained. "The opposite end of the vibratory scale and the only thing that will combat the infra-red rays that cause red spot fever. Those men won't stop walking until they've reached Shaft Four." Grannie Annie told her story during the long ride back to Shaft Four. For he knew that just as Jupiter's great spot was responsible for a climate and atmosphere suitable for an Earthman on this Eighth Moon, so also was that spot a deadly power in itself, capable when its rays were concentrated of causing a fatal sickness. Then suddenly becoming fearful of Grannie's prying, Antlers Park strove He did head her off and managed to lure her and Baker and Xartal into the Shaft barracks where they would be exposed to the rays from the lens button. But Grannie only pretended to contract the plague.

<question>:
What is true about the Red Spot Fever?

<options>:
A It is contagious, and it is affecting nearly every worker.
B There is no known cure for it.
C It makes people vanish into thin air.
D Infra-red rays influence people, and they end up lost in the Baldric.

<answer>:

D