题目

    People have wondered for a long time how their personalities and behaviors are formed. It’s not easy to explain why one person is intelligent and another is not, or why one is cooperative and another is competitive.        Social scientists are, of course, extremely interested in these types of question. They want to explain why we possess certain characteristics and exhibit certain behaviors. There are no clear answers yet, but two distinct schools of thought on the matter have developed. As one might expect, the two approaches are very different from each other, and t方程x＝x(x－3)的根是 [　　] A．x＝4B．x＝0 C．x1＝4，x2＝0D．无解