How to add an audio file to a button in Unity3D

using UnityEngine;

using System.Collections;

using System;

public class MainMenu : MonoBehaviour {

public AudioSource audioSource;

public AudioClip palySound;

void Start ()  { }

public void OnGUI()

{  if(GUI.Button(new Rect(50,200,100,45),”Play”))  {

audioSource.PlayOneShot(palySound); }

}}

when we attached the script in the inspector.

we have to attach the AudioSource  from the

Components–>Audio–>AudioSource

to the inspector