下列类ABC中所定义的构造函数，错误的是（ ）。

A、class ABC{private:
int x, y;public:
ABC( )
{
x = 0;
y = 0;
}
ABC(int a, int b)
{
x = a;
y = b;
} };;
B、class ABC{private:
int x, y;public:
ABC( )
{
x = 0;
y = 0;
}
ABC(int a, int b);};AB
C、:ABC(int a, int b)
{
x = a;
y = b;
};
C、class ABC{private:
int x, y;public:
ABC(int a = 0, int b = 0);};AB
C、:ABC(int a, int b)
{
x = a;
y = b;
};
D、class ABC{private:
int x = 0, y = 0;public:
void Abc(int a, int b)
{
x = a;
y = b;
}};