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, I was running in circles—especially since Grannie became twins every now and then. 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 Grannie Annie was the original research digger-upper, and when she 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. I walked forward to get a closer view of one of the flagpole trees. And And then all at once Grannie stopped again, this time at the top of a 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 to be a high-flying cockatoo. As that dot continued to move across the heavens in a single direction, I called Grannie's attention to it. "It's a kite," she nodded. "There should be a car attached to it somewhere." She offered no further explanation, but a quarter of an hour later as we topped another rise a curious elliptical car with a long slanting windscreen came into view. Attached to its hood was a taut wire which slanted up into the sky to connect with the kite. A man was driving and when he saw us, he waved. Five minutes later Grannie was shaking his hand vigorously and mumbling introductions. 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 electric windlass to which the kite wire was attached. Apparently these 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 "But surely you must have some idea of where they go," Grannie said. ahead of us." I followed his gaze and saw a curious structure suspended between a rude circle of flagpole trees. A strange web-like formation of translucent gauzy material, it was. Fully two hundred cockatoos were perched upon it. They watched us with their mild eyes as we passed, but notebook out, sketching the room's interior. Grannie Annie remained Grannie Annie walked across to it and began to study its markings. Grannie nodded. "I think you and I and Xartal had better take a run up dynamo that would operate on a kite windlass, and a quantity of wire and other items. The kite car was brought out again, and the old woman, Baker and the Martian took their places in it. Then Jimmy waved, and the car began to roll down the ramp. Not until they had vanished in the desert haze did I sense the foreboding. Had I been a fool to let Grannie go? I thought of her, an coalesced into a three-dimensional scene. It was a scene of a rapidly unfolding desert country as seen from the rear of a kite car. Directly behind the windscreen, backs turned to me, were Jimmy Baker, Grannie, and Xartal. It was as if I were standing directly behind them. Then once more I was directly behind my friends, listening in on their conversation. The view through the windscreen showed an irregular array 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." Moments later a rude circle of flagpole trees loomed ahead. Across the 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 plot. Look at that damned nosy bird! " A silver cockatoo had alighted on the kite car and was surveying curiously Xartal's work. As each drawing was completed, the bird scanned it with rapt attention. Abruptly it flew to the top of the 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 "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 Back in the visiscreen room, I snapped to the operator: "Turn it on!" The kite car swam into view in the screen above the instrument panel. 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 "Ezra," I said, "we're going to drive out and meet them. There's 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 across the desert, and a growing suspicion began to form in my mind. "Ezra!" I yelled, swinging the car. "That wasn't Grannie! That was one of those damned cockatoo images. We've got to catch him." The other car was some distance ahead now. Park looked back and saw us following. He did something to the kite wire, and his car leaped ahead. I threw the speed indicator hard over. Our kite was a huge box affair with a steady powerful pull to the connecting wire. Park's vehicle was drawn by a flat triangular kite that dove and fluttered with each variance of the wind. Steadily we began to close in. The manager of Interstellar Voice turned again, and something glinted appeared in our windscreen inches above Karn's head. "Heat gun!" Ezra yelled. Now we were rocketing over the sand dunes, winding in and out between the flagpole trees. I had to catch that car I told myself. Grannie Annie's very life might be at stake, not to mention the lives of hundreds of mine workers. Again Park took aim and again a hole 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 speed, I raced alongside. The I. V. manager lifted his weapon frantically. But before he could trigger. Weakly he lifted an arm and pointed to the northwest. "Val-ley. Thir-ty miles. Entrance hidden by wall of ... flagpole trees." I leaped into the driver's seat and gave the kite its head. And now the country began to undergo a subtle change. The trees seemed to group themselves in a long flanking corridor in a northwesterly direction, as a mile forward and the desert began "Grannie!" I yelled. "What're you doing here? Where's Mr. Baker?" "Don't look so fuddled, Billy-boy. Come along, and I'll show you." Larynx miners. They walked slowly, looking straight ahead, moving down the center of the gorge toward the entrance. But there was more! A kite car was drawn up to the side. The windscreen 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 Grannie Annie told her story during the long ride back to Shaft Four. Then suddenly becoming fearful of Grannie's prying, Antlers Park strove to head her off before she reached Shaft Four. 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. Park then attempted to outwit Ezra Karn and me by returning in Jimmy Baker's kite car with a cockatoo image of Grannie.

<question>:
What was the point in Grannie Annie and Billy-boy venturing into the desert?

<options>:
A They were there to find Baker
B They were trying to locate the strange birds
C They were looking for proof of the Red Spot Fever
D They were trying to locate the kites

<answer>:

A