I did it this way. How can I improve this?

var questionAnswer = [
  ['Which planet is the closest to the Sun?', 'mercury'],
  ['What\'s the best coding language?', 'javascript'],
  ['What\'s the name of fourth farthest planet from the Sun', 'mars']  
];
var answerCorrect = 0;
var answerWrong = questionAnswer.length; 
var whichRight = "<p> You answered the following correctly: <p> <ol>";
var whichWrong = "<p> You answered the following incorrectly: <p> <ol>";
var results = "<p> You answered " + answerCorrect + " correctly and " + answerWrong + " incorrectly.</p>"; 

function print(message) {
  document.write(message);
}

for( var i = 0; i < questionAnswer.length; i += 1) {
    userAnswer = prompt(questionAnswer[i][0]); 
    if ( userAnswer.toLowerCase() === questionAnswer[i][1]) {
         answerCorrect += 1;
         answerWrong -= 1; 
         whichRight += "<li>" + questionAnswer[i][0] + "</br></li>";
   }  
    else if ( userAnswer.toLowerCase() !== questionAnswer[i][1]) {
        questionsWrong = questionAnswer.indexOf(userAnswer.toLowerCase());
          if ( questionsWrong < 0 ) {
            whichWrong += "<li>" + questionAnswer[i][0] + "</br>" + " The answer is " + questionAnswer[i][1] + "</li>";
      }
   } 
}

if (answerCorrect === 0) {
  whichRight += "Sorry! You answered all questions incorrectly. Please try again."
} else if (answerCorrect === questionAnswer.length) {
  whichWrong += "Congrats! You answered everything correctly!"
}

whichWrong += "</ol>";
whichRight += "</ol>";

print(whichRight);

print(whichWrong);

print(results);