题目

Benjamin West, the father of American painting, showed his talent for art when he was only six years of age. But he did not know about brushes before a visitor told him he needed one. In those days, a brush was made from camel’s hair. There were no camels nearby. Benjamin decided that cat hair would work instead. He cut some fur from the family cat to make a brush. The brush did not last long. Soon Benjamin needed more fur. Before long, the cat began to look ragged （蓬乱）. His father said that the cat must be sick. Benjamin was forced to admit what he had been doing. The cat’s 孟德尔在豌豆杂交实验中，发现问题和验证假说所采用的实验方法依次是 A. 自交、杂交和测交                     B. 测交、自交和杂交 C. 杂交、自交和测交                     D. 杂交、测交和自交