单项选择题

下面这个程序的结果是
  #include<iostream.h>
  classA
  
    private:
      inta;
    public:
      voidseta( );intgeta( );;
  voidA::seta( )
  a=1;
  intA::geta( )
  returna;
  classB
   private:
    inta;
   publiC:
    voidseta( );intgeta( );;
  voidB::seta( )
  a=2;
  intB::geta( )
  returna;
  classC:publicA,publicB
   private:
      intb;
    public:
      voiddisplay( );;
  voidC::display( )
   int b:geta( );
    cout<<b;
  voidmain( )
    Cc;
    c.seta( );
    c.display( );

A.1
B.2
C.随机输出1或2
D.程序有错