题目

阅读下列短文，从每题所给的四个选项（A、B、C和D）中选出最佳选项。 Women are friendly. They often share with others. But men are more competitive. They are trying to improve their social status. Why? Researchers have found it's all due to the hormone oxytocin (荷尔蒙催生素). Although known as the love hormone, it affects the sexes differently. Generally, people believe that the hormone oxytocin is let out in our body in various social situations and our body creates a large amount of it when falling in love or giving birth. But in a former experiment Professor已知含5个数的组数1，2，3，4，a的平均数是3，则该数组的方差是（　　）A．1B．10C．4D．2