单选题 When a rare disease ALD threatened to kill the four-year-old boy Lorenzo, his parents refused to give up hope. Doctors explained that there was no cure for ALD, and that he would probably die within three years. But Lorenzo"s parents set out to prove the doctors wrong. The parents devoted themselves to keeping their son alive and searching for a cure. But doctors and the families of other ALD patients often refused to take them seriously. They thought the efforts to find a cure were a waste of time, and drug companies weren"t interested in supporting research into such a rare disease. However, the parents still refused to give up and spent every available hour in medical libraries and talking to anyone who would help. Through trial and error (反复实验)， they finally created a cure from ingredients (调料) commonly found in the kitchen. The cure, named "Lorenzo"s Oil", saved the boy"s life. Despite the good results, scientists and doctors remained unconvinced. They said there was no real evidence that the oil worked and that the treatment was just a theory. As a result, some families with ALD children were reluctant to try it. Finally, the boy"s father organized an international study to test the oil. After ten years of trials, the answer is: the oil keeps ALD children healthy. (224 words)

单选题 Doctors said that Lorenzo might die within three years because______.

单选题 The families of other ALD patients thought that______.

单选题 Scientists and doctors believed that Lorenzo"s Oil______.

单选题 Lorenzo"s father organized an international study to______.

单选题 From the passage we can conclude that______.