有下列程序： #include＜iostream＞ using namespace std; class Complex double re,im; public: Complex(double r,double i):re(r),im(i) double real()constretum re; double image()constreturn im; Complex& operator+=(Complex
A．
re+=a.re;
im+=a.im;
return*this;
;
ostream& operator＜＜(ostream& s,const Complex& z)
return s＜＜’(’＜＜z.real()《’,’＜＜Z.image0＜＜’)’;
int main()
Complex x(1,2)，y(2,3);
cout＜＜(x+=y)＜＜endl;
return 0;
执行这个程序的输出结果是( )。A) (1,-2)
B．(2,3)
C．(3,5)
D．(3,1)