Controller.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Controller : MonoBehaviour
{
    public GameObject obs1;
    public GameObject obs2;
    public GameObject obs3;
    public GameObject obs4;
    public GameObject PositionofNewObsticle;
    int counter = 0;

   
    private void OnTriggerEnter2D(Collider2D collision)
    {
        counter = Random.Range(1, 5);
        if (collision.gameObject.tag == "obsticle")
        {
            if(counter == 1)
            {
                Instantiate(obs1, new Vector2(PositionofNewObsticle.transform.position.x, obs1.transform.position.y), Quaternion.identity);
            }
            else if(counter == 2)
            {
                Instantiate(obs2, new Vector2(PositionofNewObsticle.transform.position.x, obs2.transform.position.y), Quaternion.identity);
            }
            else if(counter == 3)
            {
                Instantiate(obs3, new Vector2(PositionofNewObsticle.transform.position.x, obs3.transform.position.y), Quaternion.identity);
            }
            else if(counter == 4)
            {
                Instantiate(obs4, new Vector2(PositionofNewObsticle.transform.position.x, obs4.transform.position.y), Quaternion.identity);
            }
            Destroy(collision.gameObject);
            return;
        }
    }
}