what is the reason that 'randomNumber1' is always assigned by '0' though i use Random.Range(0,2)

I want to randomly assign 0 or 1 to randomNumber1, but I failed with this code.

This is the code in Unity

public class Practice : MonoBehaviour
{

    public static int randomNumber1;   
    public static int randomNumber2;

    public class randd
    {
        public void randdom_dd()
        {
            int randomNumber1 = Random.Range(0, 2);
            if (randomNumber1 == 0)
            {
                int randomNumber2 = 1;
            }

            else
            {
                int randomNumber2 = 0;
            }
        }

    }

    public void OnClick()
    {
        if (randomNumber1 == 0)
        {
            print("정답!");   
        }

        else
        {
            print("틀렸어!");
        }

    }
}

I think, when I play the codes, randomNumber1 has always same int. I've tried to change the min and max in Random.Range(min, max) and some tries, I failed.