Which of the following statement is correct about the program given below?

#include<iostream.h>
class AptitudeCrack
{
    int x, y, z; 
    public:
    AptitudeCrack(int x = 100, int y = 30, int z = 0)
    {
        this->x = x; 
        this->y = y;
        this->z = z; 
        Display();
    }
    void Display()
    {
        cout<< x << ' ' << y << ' ' << z;
    }
};
int main()
{
    int a = 0, b = 1, c = 2; 
    int &x = ++a; 
    int &y = --b; 
    int z = c + b - -c; 
    AptitudeCrack objAptitude(x, y, z); 
    return 0; 
}