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

<passage>:
Planet Stories Spring 1945. Extensive research did not uncover any evidence that We had left the offices of Interstellar Voice three days ago, Earth time, and now as the immense disc of Jupiter flamed across the sky, 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. , and other works of science fiction. Blood-and-thunder as these books are, however, they have one redeeming feature—authenticity of background. Grannie Annie was the original research digger-upper, and when she laid the setting of a yarn on a star of the sixth magnitude, only a transportation-velocity of less than light could prevent her from Interstellar Voice . And then I was shaking hands with Antlers Park, the manager of I. V. himself. "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 I scowled at that it didn't make sense. "However, as you perhaps know, the only reason for colonial activities 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. The Martian speaks as the Earthman does, but he amplifies his thoughts' transmission by way of wave lengths as high as three million vibrations per second. The trouble is that by the time the average Martian reaches 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." "What do you mean?" Park leaned back. "The rush to find more of the ore," he explained. "But up until now this moon is the only place where it can be found. "There are two companies here," he continued, " Interstellar Voice and . 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 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 on foot with only the barest necessities in the way of equipment and supplies. didn't. In some strange way the thing was a hideous caricature. "Look what I found," I yelled. "What I found," said the cockatoo in a very human voice. party of four persons. In the lead was a little old lady in a black dress. Behind her strode a grizzled Earth man in a flop-brimmed hat, another Earth man, and a Martian. by some chemical radiations," she replied. "Whatever it is, we'd better watch our step. There's no telling what might lie ahead." "This is Jimmy Baker," she said. "He manages Larynx Incorporated , and he's the real reason we're here." "I can't tell you how glad I am you're here, Grannie," he said. "If anybody can help me, you can." Grannie's eyes glittered. "Trouble with the mine laborers?" she questioned. Jimmy Baker nodded. He told his story over the roar of the wind as we headed back across the desert. Occasionally he touched a stud on an has been bewitched," he began slowly. "We pay our men high wages and give them excellent living conditions with a vacation on Callisto every year. translucent gauzy material, it was. Fully two hundred cockatoos were perched upon it. They watched us with their mild eyes as we passed, but to produce during a period of thirty days or more, and you lose all rights." comparatively short time ago. Struck a rich vein of Acoustix that Interstellar Voice , our rival, in a year." and other items. neither would her millions of readers. Ezra Karn and I went back into the office. The old prospector chuckled. "Dang human dynamo. Got more energy than a runaway comet." , and through glass doors I could see clerks busy with counting machines and report tapes. In another chamber the extremely light Acoustix ore was being packed into big cases and marked for shipment. At the far end a door to a small room stood open. Inside a young man was tilted back in 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." of flagpole trees, with the sky dotted by high-flying cockatoos. "There's an eyrie over there," Jimmy Baker was saying. "We might as well camp beside it." plot. companions. And then abruptly it happened. The cockatoos took off in mass flight. A group of Earth people suddenly materialized on the eyrie, talking and moving about as if it were the most natural thing in the world. With a shock I saw the likeness of myself The real They're Xartal's drawings!" "Don't you see," the lady continued. "Everything that Xartal put on paper has been seen by one or more of these cockatoos. The cockatoos are like Earth parrots all right, but not only have they the power 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." I stared with open eyes. Jimmy Baker no longer was in the car, nor was Xartal, the Martian. Grannie Annie was there, but seated at the controls was Antlers Park, the manager of Interstellar Voice. Ezra Karn jabbed my elbow. "Grannie's coming back. I thought she'd be across the desert, and a growing suspicion began to form in my mind. Then, like a knife thrust, the truth struck me. The manager of Interstellar Voice turned again, and something glinted in his hand. There was a flash of purple flame, and a round hole granite, the way ahead utterly devoid of vegetation. In the distance black bulging hills extended to right and left, with a narrow chasm or doorway between. with an exclamation of astonishment. There was a huge chair-shaped rock there, and seated upon it was "Grannie!" I yelled. "What're you doing here? Where's Mr. Baker?" She rose to her feet and clambered down the rock. "Getting back Jimmy's mine laborers," she said, a twinkle in her eyes. "I see you've got Antlers Park. I'm glad of that. It saves me a lot of trouble." She took off her spectacles and wiped them on her sleeve. Larynx miners. They walked slowly, looking straight ahead, moving down the center of the gorge toward the entrance. vibratory scale and the only thing that will combat the infra-red rays We drove slowly, keeping the line of marching Larynx miners always ahead of us. Jimmy Baker had struck a new big lode of Acoustix, a lode which if worked successfully would see become a far more powerful exporting concern than Interstellar Voice . Antlers Park didn't want that. barracks. 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.

<question>:
Why is Acoustix so valuable?

<options>:
A Acoustix can be sold at a high price.
B It's an ore that can only be found in one place.
C It helps Martain people regain their ability to communicate.
D It's an abundant ore that Earth people sell.

<answer>:

C