The nurse notices that a client with obsessive-compulsive disorder washes his hands for long periods each day. How should the nurse respond to this compulsive behavior（）

A. By designating times during which the client can focus on the behavior.

B. By urging the client to reduce the frequency of the behavior as rapidly as possible.

C. By calling attention to or attempting to prevent the behavior.

D. By discouraging the client from verbalizing anxieties.

对于曲线y=f(x)，试在横坐标a与a+h之间找一点ξ，使在这点两边阴影部分面积相等(如图1)。