题目

阅读下面短文，从短文后所给的A、B、C三个选项中选出能填人相应空白处的最佳选项。 Joey O'Leary, a ten-year-old boy, lived in asmall town, in the USA. He had a pair of green pants that he 1 most, but the pants were already short forhim. One day, his father thought of a(n) 2. He said to Joey, Let's put yourgreen pants into a big bottle(瓶子), and then float it 3 theriver. We can put a note with your name and 4. So whoever finds the pants will knowthat they are your favourite pants. Joey thought that it was a5 idea, so they just did that.The bottle floated forwe遗传信息的载体是一种叫做DNA 的有机物。                        （   ）