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. constructA   destructA
B. constructA   constructA   destructA   destructA
C. constructA   constructA   constructA   destructA   destructA   destructA
D. constructA   constructA   constructA   constructA   destructA   destructA   destructA   destructA