Please HELP: ¿How can i made a drag and drop quiz?, i got some problems whit my scripts, like connecting the drag and drop function whit the buttons

I'm working on a 2D drag and drop quiz, the idea is that the icons on the pickup, upon contacting the trailer, give the correct answer, but i can't use the drag and drop script i made.

¿How can i drop and destroy the answer whit another object?

And, ¿how can i change the question, once it was answer?

//THIS IS MY GAME MANAGER

using System.Collections; using System.Collections.Generic; using UnityEngine; using System.Linq; using UnityEngine.UI;

public class GameManager : MonoBehaviour {

 public TestQuestions [] questions;

 private static List <TestQuestions> unAnsweredQuestions;

 private TestQuestions currentQuestion;

 [SerializeField]
 private Text factText;




 void Start(){
     if (unAnsweredQuestions == null || unAnsweredQuestions.Count == 0){
         unAnsweredQuestions = questions.ToList<TestQuestions>();
     }

     SetCurrentQuestion ();
     /*Debug.Log (currentQuestion.fact + " is " + currentQuestion.isTrue);*/
 }

 void SetCurrentQuestion () {
     int randomQuestionIndex = Random.Range (0, unAnsweredQuestions.Count); 
     currentQuestion = unAnsweredQuestions [randomQuestionIndex];

     factText.text = currentQuestion.fact;

     unAnsweredQuestions.RemoveAt (randomQuestionIndex);
 }



 public void UserSelectTrue (){
     if (currentQuestion.isTrue) {
         Debug.Log ("Correct");
     } else {
         Debug.Log ("Wrong");

     }
         
 }

 public void UserSelectFalse (){
     if (!currentQuestion.isTrue) {
         Debug.Log ("Correct");
     } else {
         Debug.Log ("Wrong");

     }

 }

}

//AND THIS IS MY DRAG AND DROP SCRIPT

using System.Collections; using System.Collections.Generic; using UnityEngine;

public class Icons : MonoBehaviour { private Vector3 screenpoint;

 void OnMouseDown(){
     screenpoint = Camera.main.WorldToScreenPoint (gameObject.transform.position);
 }

 void OnMouseDrag (){
     Vector3 currentScreenPoint = new Vector3 (Input.mousePosition.x, Input.mousePosition.y, screenpoint.z);
     Vector3 currentPos = Camera.main.ScreenToWorldPoint (currentScreenPoint);
     transform.position = currentPos;
 }

}