Getting random question at a maximum of 10 in a pool of question quiz game [help]

So I have followed the tutorial of the Unity Quiz game and wondered that If i want the game to present only up to 10 questions but the pool of questions have 20 or so so this is the script from the tutorial that I have somewhat edited. using UnityEngine; using UnityEngine.UI; using UnityEngine.SceneManagement; using System.Collections.Generic;

public class AdditionGameController : MonoBehaviour { public AdditionSimpleObjectPool answerButtonObjectPool; public Text questionText; public Text scoreDisplay; public Text timeRemainingDisplay; public Transform answerButtonParent;

 public GameObject questionDisplay;
 public GameObject roundEndDisplay;
 public Text highScoreDisplay;
 private AdditionDataController dataController;
 private AdditionRoundData currentRoundData;
 private AdditionQuestionData[] questionPool;
 private bool isRoundActive = false;
 private float timeRemaining;
 private int playerScore;
 private int questionIndex;
 private List<GameObject> answerButtonGameObjects = new List<GameObject>();
 private List<int> unselectedIndices= new  List<int> ();

 void Start()
 {
     dataController = FindObjectOfType<AdditionDataController>();                                // Store a reference to the DataController so we can request the data we need for this round
     currentRoundData = dataController.GetCurrentRoundData();                            // Ask the DataController for the data for the current round. At the moment, we only have one round - but we could extend this
     questionPool = currentRoundData.questions; 

     for (int i = 0; i < questionPool.Length; i ++)                                // For every AnswerData in the current QuestionData...
     {
         unselectedIndices.Add(i);
     }
     timeRemaining = currentRoundData.timeLimitInSeconds;                                // Set the time limit for this round based on the RoundData object
     UpdateTimeRemainingDisplay();
     playerScore = 0;
     questionIndex = UnityEngine.Random.Range(0,unselectedIndices.Count);
     ShowQuestion();
     isRoundActive = true;
 }
 void Update()
 {
     if (isRoundActive)
     {
         timeRemaining -= Time.deltaTime;                                                // If the round is active, subtract the time since Update() was last called from timeRemaining
         UpdateTimeRemainingDisplay();
         if (timeRemaining <= 0f)                                                        // If timeRemaining is 0 or less, the round ends
         {
             EndRound();
         }
     }
 }
 void ShowQuestion()
 {
     RemoveAnswerButtons();
     AdditionQuestionData questionData = questionPool[unselectedIndices[questionIndex]];                            // Get the QuestionData for the current question
     questionText.text = questionData.questionText;                                        // Update questionText with the correct text
     for (int i = 0; i < questionData.answers.Length; i ++)                                // For every AnswerData in the current QuestionData...
     {
         GameObject answerButtonGameObject = answerButtonObjectPool.GetObject();            // Spawn an AnswerButton from the object pool
         answerButtonGameObjects.Add(answerButtonGameObject);
         answerButtonGameObject.transform.SetParent(answerButtonParent);
         answerButtonGameObject.transform.localScale = Vector3.one;
         AdditionAnswerButton answerButton = answerButtonGameObject.GetComponent<AdditionAnswerButton>();
         answerButton.SetUp(questionData.answers[i]);                                    // Pass the AnswerData to the AnswerButton so the AnswerButton knows what text to display and whether it is the correct answer
     }
 }
 void RemoveAnswerButtons()
 {
     while (answerButtonGameObjects.Count > 0)                                            // Return all spawned AnswerButtons to the object pool
     {
         answerButtonObjectPool.ReturnObject(answerButtonGameObjects[0]);
         answerButtonGameObjects.RemoveAt(0);
     }
 }
 public void AnswerButtonClicked(bool isCorrect)
 {
     if (isCorrect)
     {
         playerScore += currentRoundData.pointsAddedForCorrectAnswer;                    // If the AnswerButton that was clicked was the correct answer, add points
         scoreDisplay.text = playerScore.ToString();
     }

     unselectedIndices.RemoveAt(questionIndex);
     if(unselectedIndices.Count>0)                                           // If there are more questions, show the next question
     {
         questionIndex= UnityEngine.Random.Range(0,unselectedIndices.Count);
         ShowQuestion();
     }
     else                                                                                // If there are no more questions, the round ends
     {
         EndRound();
     }
 }
 private void UpdateTimeRemainingDisplay()
 {
     timeRemainingDisplay.text = Mathf.Round(timeRemaining).ToString();
 }
 public void EndRound()
 {
     isRoundActive = false;
     questionDisplay.SetActive(false);
     roundEndDisplay.SetActive(true);
 }
 public void ReturnToMenu()
 {
     SceneManager.LoadScene("MenuScreen");
 }

}