How do I rotate an instantiated prefab?

Unity Engine
1

Hello !

Iv’e made a script so I can instantiate a prefab at my current mouse position for my building game.
But right now the prefab only have one rotation and when I press “R” I want to rotate it 90 deg.
This is my current code for instantiating a prefab.

    private Transform currentBuilding;
    private Grid grid;
    void Awake()
    {
        grid = FindObjectOfType<Grid>();  
    }

    void Update()
    {
        if (currentBuilding != null)
        {
            Vector3 m = Input.mousePosition;
            m = new Vector3(m.x, m.y, transform.position.y);
            Vector3 p = grid.GetNearestPointOnGrid(GetComponent<Camera>().ScreenToWorldPoint(m));
            currentBuilding.position = new Vector3(p.x, 0, p.z);
        }

    }

    public void SetItem(GameObject b)
    {
 
        currentBuilding = ((GameObject)Instantiate(b)).transform;

    }

Any ideas on how I can rotate the instantiated prefab?

2

Try this?

and