Error - An Object Reference is Required to Access Non-Static Member

Please halp me fix this…“GameController.AddScore()”

using UnityEngine;
using System.Collections;

public class DestroyScript : MonoBehaviour{
public GameController gc;
public GameObject Explosion;

void Start(){
	gc = GameObject.FindGameObjectWithTag ("Player").GetComponent<GameController>();
}

void OnTriggerEnter (Collider Other)
{
	if(Other.tag == "Player")
	{
		Instantiate (Explosion,transform.position, transform.rotation);
		GameController.AddScore();
		Destroy(gameObject);
	}
}

}

Hello.
I think that you should rewrite at 10 line.

gc.AddScore();

I recommend that you watch this tutorial video.
http://unity3d.com/jp/learn/tutorials/modules/beginner/scripting/getcomponent