题目

 When it comes to success in business and success in life, there are few qualities as important as confidence．  People naturally have different levels of confidence．Some have a higher level of confidence than others do, but even those whose confidence is lacking can learn to build their level of confidence and reach their most important goals．Increasing self confidence is one of the most common reasons people give for seeking the help of psychologists and other professionals．  One of the many places where a greater level of confidence is useful is in the workplace．We all k10个人围成一圈每人想一个自然数，并告诉在他两边的人，然后每人将他两边的人告诉他的数的平均数报出来，报的结果如图，则报13的人心想的数是（　　）A．12B．14C．16D．18