Rotate Clicked Gameobject / Perhab

Hello, I'm working on a memory game and my current problem is. If I click on a memory block all will turn around and not the selected one. :(

This is my code:

 using UnityEngine;
 using System.Collections;
 
 public class Test : MonoBehaviour {
 
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update(){
     if(Input.GetMouseButtonDown(0)){
        Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
        RaycastHit hit;
        if(Physics.Raycast(ray, out hit)){
           if(hit.collider.tag == "Memo"){
             hit.transform.Rotate(new Vector3(0,180,0));
             print("Clicked Memo" + gameObject.name);
           }
        }
     }
 }
 
 }