i have created quiz application bu tin calculation of score i am getting error
  <html>
  <head><title>gopi</title>
  <body>
  <div id="quesRes"></div>
<script>
    var quizObj = [
    { 
        "question": "What is the capital of Bangladesh?",
        "choice": ["Dhaka", "Chittagong", "Sylhet"],
        "correct":  0
   },
   { 
        "question": "What does 2+2 equal to?",
        "choice": ["3", "2", "4"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 2
   },
    { 
        "question": "What is the real name of Damon Salvatore?",
        "choice": ["Paul Wesley", "Steven McQueen", "Ian Somerhalder"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 2
   },
    { 
        "question": "What is the name of the largest planet in the universe?",
        "choice": ["Earth", "Jupiter", "Uranus"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 1
   },
    { 
        "question": "What is the capital of New York?",
        "choice": ["Manhattan", "NYC", "Albany"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 2
   },
    { 
        "question": "How many bones does the human body have?",
        "choice": ["109", "206", "114"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 1
   },
    { 
        "question": "What is the alter ego of Batman?",
        "choice": ["Bruce Banner", "Bruce Wayne", "Tony Stark"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 1
   },
    { 
        "question": "How many books are there in the Harry Potter series?",
        "choice": ["7", "5", "8"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 0
   },
    { 
        "question": "What is Naruto's surname?",
        "choice": ["Sarutobi", "Uchiha", "Uzumaki"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 2
   },
    { 
        "question": "What is the name of Sherlock Holmes' partner?",
        "choice": ["Peterson", "Watson", "Hanson"],  //quizObj[2].choice[0],quizObj[2].choice[1]
        "correct": 1
   },
];
  var track = [];
    var maxQues = prompt("How many questions do you want to answer?", "5");
    var rand = Math.floor(Math.random() * maxQues);
    var str='<h4>Answer all the questions</h4>';
    for(var i=0;i<maxQues;i++){
        var rand = Math.floor(Math.random() * maxQues);
        str+=(i+1)+'.  '+quizObj[rand].question+'<br>';
        str+='<form><table>'+
            '<tr><td id="a1"><input type="radio" name="radio' + i + '"/>'+'  '+quizObj[rand].choice[0]+'</td></tr>'+
            '<tr><td id="a2"><input type="radio" name="radio' + i + '" />'+'  '+quizObj[rand].choice[1]+'</td></tr>'+
            '<tr><td id="a3"><input type="radio" name="radio' + i + '"/>'+'  '+quizObj[rand].choice[2]+'</td></tr>'+
        '</table></form><br>';
    track[i]=rand;
    }
    str += '<input value="Submit" type="button" onclick="scoreMe()"><br><br>';
    str += 'Score: <input id="score" type="text" size="8" ><br><br><br>';
    document.getElementById('quesRes').innerHTML = str;
  function scoreMe(){
    var sum=0;
    for(var j=0;j<maxQues;j++){
      for(var k=0;k<3;k++){
        if(quizObj[track[j]].choice[k].checked===quizObj[track[j]].correct[0]){
          console.log('Works'+j);
          sum++;
        }
      }
    }
    document.getElementById('score').value = ((sum/maxQues)*100)+'%';
  }
</script>
</body>
</head>
</html>