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

<passage>:
fever, talking cockatoos and flagpole trees, 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 Xartal, the Martian illustrator, said nothing. He was like that, taciturn, speaking only when spoken to. however, they have one redeeming feature—authenticity of background. 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. "There are two principal forms of life in the Baldric flagpole trees and a species of ornithoid resembling cockatoos. So far no one has on foot with only the barest necessities in the way of equipment and supplies. Silver in plumage, it resembled a parrot with a crest and yet it 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. The cockatoo repeated my last statement again, then rose on its short legs, flapped its wings once and soared off into the sky. Xartal, the Martian illustrator, already had a notebook in his hands and was sketching a likeness of the creature. cockatoos and more flagpole trees. Above us, the great disc of Jupiter tell me what you see." dress. Behind her strode a grizzled Earth man in a flop-brimmed hat, another Earth man, and a Martian. Detail for detail they were a duplicate of ourselves! "A mirage!" said Ezra Karn. But it wasn't a mirage. As the party came closer, we could see that their lips were moving, and their voices became audible. I listened in awe. The duplicate of myself was talking to the duplicate of Grannie Annie, and she was replying in the most natural way. Steadily the four travelers approached. Then, when a dozen yards away, to be a high-flying cockatoo. As that dot continued to move across the he was tall and lean, with pleasant blue eyes which even his sand goggles could not conceal. adjustments moved planes or fins on the kite and accounted for the car's ability to move in any direction. "If I weren't a realist, I'd say that Larynx Incorporated 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 none of them will hold water. By the way, there's a cockatoo eyrie translucent gauzy material, it was. Fully two hundred cockatoos were perched upon it. They watched us with their mild eyes as we passed, but they didn't move. a swivel chair before a complicated instrument panel. "C'mon in," he said, seeing us. "If you want a look at your friends, here they are." 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. It was a scene of a rapidly unfolding desert country as seen from the were Jimmy Baker, Grannie, and Xartal. It was as if I were standing directly behind them. "It's Mr. Baker's own invention," the operator said. "An improvement on the visiphone." "Do you mean to say you can follow the movements of that car and its passengers wherever it goes? Can you hear them talk too?" "Sure." The operator turned another dial, and Grannie's falsetto voice The cloud of anxiety which had wrapped itself about me disappeared somewhat as I viewed this device. At least I could now keep myself posted of Grannie's movements. of flagpole trees, with the sky dotted by high-flying cockatoos. top of them was stretched a translucent web. Jimmy and Grannie got out of the car and began making camp. Xartal remained in his seat. He was drawing pictures on large pieces of pasteboard, and as I stood there in the visiscreen room, I watched him. There was no doubt about it, the Martian was clever. He would make a few rapid lines on one of the pasteboards, rub it a little to get the proper shading and then go on to the next. In swift rotation likenesses of Ezra Karn, of myself, of Jimmy Baker, and of Antlers Park took form. Ezra spoke over my shoulder. "He's doing scenes for Grannie's new A silver cockatoo had alighted on the kite car and was surveying 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 I saw Ezra Karn and I saw the image of Jimmy Baker. The real Jimmy Baker stood next to Grannie, staring up at this incredible mirage. Grannie let out a whoop. "I've got it!" she said. "Those things we see up there are nothing more than mental images. 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 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." The Larynx manager nodded slowly. "I see," he said. "But why don't the 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. Up on the eyrie a strange performance was taking place. The duplicate of Grannie Annie was bowing to the duplicate of Jimmy Baker, and the image of Ezra Karn was playing leap frog with the image of Antlers Park. Then abruptly the screen before me blurred and went blank. "Sorry," the operator said. "I've used too much power already. Have to of those damned cockatoo images. with an exclamation of astonishment. There was a huge chair-shaped rock there, and seated upon it was "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. "Don't look so fuddled, Billy-boy. Come along, and I'll show you." gorge, it was, with the black sheer cliffs on either side pressing close. Ten feet forward, I stopped short, staring in amazement. Advancing toward me like a column of infantry came a long line of bluish radiance spewed from its open end. Playing it back and forth upon the marching men were Jimmy Baker and Xartal, the Martian. Interstellar Voice . Antlers Park didn't want that. It was he or his agents who placed those lens buttons in the Larynx barracks. capable when its rays were concentrated of causing a fatal sickness. Then suddenly becoming fearful of Grannie's prying, Antlers Park strove Baker's kite car with a cockatoo image of Grannie.

<question>:
What is so unique about the cockatoos on this planet?

<options>:
A They are able to copy speech.
B They live in abundance in the Baldric, despite it being a dangerous area.
C They are identical to Earth parrots, despite being on a different planet.
D They are able to physically mimic any picture.

<answer>:

D