单项选择题

下面程序的结果是( )。     #include<iostream.h>     class A     { public:       A( ) { cout < < "construtA" < < end1;}       virtual ~A( ) { cout < < "destructA" < < end1;} };     class B:public A     { };     class C:public A     { };     class D:public B,public C     { };     void main( )     { Dd;}

A.constructAdestructA
B.constructAconstructAdestructAdestructA
C.constructAconstructAconstructAdestructAdestructAdestructA
D.constructAconstructAconstructAconstructAdestructAdestructAdestructAdestructA