阅读下列短文,从每题所给的四个选项(A、B、C、D)中，选出最佳选项。并在答题卡上将该项涂黑。
A
Flying over a desert area in an airplane, two scientists looked down with trained eyes at trees and bushes. After an hour's flight one of the scientists wrote in his book, 'Look here for probable metal'. Scientists in another airplane, flying over a mountain region, sent a message to other scientists on the ground, 'Gold possible.' Walking across hilly ground, four scientists reported, 'This ground should be searched for metals.' From an airplane over a hilly wasteland a scientist sent back by radio one word, 'Uranium'.
None of the scientists had X-ray eyes: they had no magic powers for looking down below the earth's surface. They were merely putting to use one of the newest methods of location minerals in the ground---using trees and plants as signs that certain minerals may lie beneath the ground on which the trees and plants are growing.
