What will be the output of the following C# code?

class maths
{
    public int x;
    public double y;
    public int add(int a, int b)
    {
        x = a + b;
        return x;
    }
    public int add(double c, double d)
    {
        y = c + d;
        return (int)y;
    }
    public maths()
    {
        this.x = 0;
        this.y = 0;
    }
}    
class Program
{
    static void Main(string[] args)
    {
        maths obj = new maths();
        int a = 4;
        double b = 3.5;
        obj.add(a, a);
        obj.add(b, b);
        Console.WriteLine(obj.x + " " + obj.y);
        Console.ReadLine();
    }
}

A. 4, 3.5

B. 8, 0

C. 7.5, 8

D. 8, 7

Answer: Option D