单项选择题

下面程序的结果是   #include   class A   {   int a;   public:   A():a (1){}   void showa(){cout<<a;}   };   class B   {   int a;   public:   B():a (2){}   void showa(){cout<<a;}   };   class C:public A, public B   {   int a;   public:   C():a (3){}   void showa(){cout<<a;}   };   void main()   {   C c;   c.showa();   }

A.1
B.2
C.3
D.程序有错误