若一个圆柱的侧面展开后是一个正方形，则正方形的边长相当于圆柱的[ ]

A．底面直径和周长    

B．底面周长和高    

C．底面积和高

Since risk is associated with most projects, the best course of action is to （）.

A.cover all project risks by buying appropriate insurance

B.ignore the risks, since nothing can be done about them and move forward with the project in an expeditious manner

C.avoid projects with clear and present risk

D.identify various risks and implement actions to mitigate their