WebGL doesn't work when using UnityEngine.Advertisements

Whenever I try to build to WebGL, I receive the following error:

 Assets/Scripts/SettingsButtons.cs(98,17): error CS0246: The type or namespace name `ShowOptions' could not be found. Are you missing a using directive or an assembly reference?

Does this mean that it won't work because of the advertisements? If so, how can I have them automatically be disabled when I build to WebGL?

Here's the full script for context (It's a kind of swiss-army knife script so there's a bunch of useless stuff in there. I'll remove what I can)

 using UnityEngine;
 using UnityEngine.UI;
 using UnityEngine.Analytics;
 using UnityEngine.Advertisements;
 using System;
 using System.Collections;
 using System.Collections.Generic;
 
 public class SettingsButtons : MonoBehaviour {
 
     public bool Value;
     public Image Img;
     public Sprite EnabledSprite;
     public Sprite DisabledSprite;
 
     //Ads Stuff 
 
     public string zoneId;
 
     // Use this for initialization
     void Start () {
 
         GameObject.Find("MainMenu").GetComponent<Animator>().SetBool("Visible", true);
         GameObject.Find("ExtraMenu").GetComponent<Animator>().SetBool("Visible", false);
 
 
     }
     
     // Update is called once per frame
     void Update () {
 
 
     
     }
 
     public void ShowAd () {
         
         if (string.IsNullOrEmpty (zoneId)) zoneId = null;
 
         ShowOptions options = new ShowOptions();
         options.resultCallback = HandleShowResult;
 
         Advertisement.Show (zoneId, options);
 
     }
 
     public void ExpressAppreciation () {
         GameObject.Find("Thanks").GetComponent<Animator>().SetTrigger("Show");
     }
     public void ExpressRegret () {
         GameObject.Find("YouSuck").GetComponent<Animator>().SetTrigger("Show");
     }
     public void ExpressERROR () {
         GameObject.Find("Error").GetComponent<Animator>().SetTrigger("Show");
     }
 
     private void HandleShowResult (ShowResult result)
     {
         switch (result)
         {
         case ShowResult.Finished:
             ExpressAppreciation();
             break;
         case ShowResult.Skipped:
             ExpressRegret();
             break;
         case ShowResult.Failed:
             ExpressERROR();
             break;
         }
     }
 
 }

Thanks in advance if someone can help.