Instantiating prefabs as child of a gameobject

I have a spawner game object which spawns obstacle prefab. I'm trying to make this spawned objects childs of the spawner game object.

Here is my code;

 public class ObstacleSpawn : MonoBehaviour
 {
     public GameObject Obstacle;
     void Start()
     {
 
 
         Vector3 center = transform.position;
         for (int i = 0; i < 10; i++)
         {
             Vector3 pos = RandomCircle(center, 1.07f);
             Quaternion rot = Quaternion.FromToRotation(Vector3.down, center - pos);
             Instantiate(Obstacle, pos, Quaternion.identity);
         }
     }
     Vector3 RandomCircle(Vector3 center, float radius)
     {
         float ang = Random.value * 360;
         Vector3 pos;
         pos.x = center.x + radius * Mathf.Cos(ang * Mathf.Deg2Rad);
         pos.y = center.y;
         pos.z = center.z + radius * Mathf.Sin(ang * Mathf.Deg2Rad);
         return pos;
     }
 
 
     void Update()
     {
         
     }
 }