An object reference is required when checking for active object

So I'm trying to check to see if an object is active or not and I'm running into the CS0120 error (An object reference is required to access non-static member). My goal is to create a teleporter script that works for multiple entrances and exits. The problem is that many of the entrances are large planes that intersect or are in locations where I don't want them to be active until later.

Here is my script.

 using UnityEngine;
 using System.Collections;
 
 public class Example : MonoBehaviour 
 {
 public Transform teleportTo;
     void OnCollisionExit(Collision col) 
     {
         if (GameObject.activeSelf = true)
         {col.transform.position = teleportTo.position;}
     }
 }

Thanks in advance.