Reading Comprehension 
从下列每篇短文的问题后所给的四个选择项中选出一个最佳答案。
     A group of college students were telling frightening stories. Eventually, a girl from a small town in Michigan broke in. “I know a more frightening story than any of those!” she announced. “And the most frightening thing is, this one is true. It happened to a girl my sister knew.”
     She began her story. “One stormy evening, the girl went to baby-sit at a house way out in the country. She was feeling a little nervous when the phone rang. When she answered, a man said, ‘Have you checked the child?’ and laughed strangely. She was scared to death when a few minutes later the guy called again and said the same thing. She checked the child and called the operator to get the calls traced. Soon the operator called back to say, ‘Get out of the house! He's in the house with you!’ So she got hold of the child and ran out into the rain. Later, the police found this escaped prisoner in the parents' upstairs bedroom.”

     “But wait a minute!” called out the girl's roommate from Iowa. “That didn't happen in Michigan. It happened near my hometown long ago when my mother was in school. The guy had escaped from a madhouse.”, “Well, it sounds an awful lot like something that happened a few years ago to a friend of my brother's in Colorado,” said another student. “Only the guy actually caught the babysitter.”
     What's going on here? How could the same event have happened to three different babysitters in three different parts of the country at three different times? It is what we call urban legend（都市传奇）, which is the modern version of American folk tales. Urban legends are modern and sound real to us. They are humorous, unexpected, and often frightening, though they probably never happened.