假设已经定义好了类student，现在要定义类derived,它是从student私有派生的，则定义类derived的正确写法是
A、class derived：student private{ //............}
B、class derived：student public { //............}
C、class derived：public student { //............}
D、class derived：private student{ //...........}
【正确答案】：D
