题目

In early January this year, the rate of UFO reports were steady, around three per weeks(week). When however, on Monday, January 16. a science fiction film about visitors to outer space was shown on television, there was the  immediate increase in reports of sightings from all parts of the States. The commanding officer, Wayne Tyler, who directly responsible for the study of all such reports, decided to making  his findings known. They wrote an article, which said that all UFO reports could be explained for quite naturally by aircraft movements. Follow this explanation, there was a ra已知复数，则的共轭复数是 A．　         B．           C．            D．