What is the value of _number after the code is executed?

C is the correct answer

Hi,
I tried code above:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _010_Class_Number
{
class Program
{
static void Main(string[] args)
{
ANumber mynumber = new ANumber(3);
Console.WriteLine(mynumber);
Console.ReadLine();
}
public class ANumber
{
private int _number = 7;
public ANumber()
{
}
public ANumber(int number)
{
_number = number;
}
//public static implicit operator int(ANumber a)
//{
// return a._number;
//}
}
}
}

Output: _010_Class_Number.Program+ANumber
And when I add implicit operator it works!
Am I doing something wrong?

Thanks!