GUIText in Unity 4.6.9

While working on my game, I was programming the score as a variable.

 using UnityEngine;
 using System.Collections;
 
 public class Game_Controller : MonoBehaviour {
 
     public GUIText ScoreText;
     public int Score;
 
     void Start () {
     
         Score = 0;
         UpdateScore ();
 
     }
 
     public void Addscore (int newScoreValue){
         Score += newScoreValue;
         UpdateScore ();
     }
 
 
     void UpdateScore () {
     
         ScoreText.text = "Score: " + Score;
 
     }
 }

After I wrote that I looked at the empty object I attached this script to. When I looked in the optinos menu, the Text for my canvas was not available as an option

How should I work around this?