My Solution for the "Build a Quiz Challenge" (and a few questions)

Well this is the solution I derived:

var quiz = [
  ["What is 3 + 5?", "8"],
  ["How many continents are there?", "7"],
  ["What comes after life?", "death"]
];
var question;
var score = 0;
var correctAnswers = "";
var wrongAnswers = "";

//Function for ease of printing to doc.
function print(message) {
  document.write(message);
}

//Prompting the Quiz Questions and Storing Ans.
for (var i = 0; i < quiz.length; i += 1) {
  question = prompt( quiz[i][0] );
  question = question.toLowerCase();

  if (question === quiz[i][1]) {
    correctAnswers += "<li>You answered \"" + quiz[i][0] + "\" correctly!</li>"
    score += 1;
  } else {
   wrongAnswers += "<li>You failed to get \"" + quiz[i][0] + "\" correct.</li>"
  }
}

//"Your Score" Message
print("You got " + score + " question(s) right.");

//Correct Answers
print("<h2>You got these questions correct:</h2>");
var correctList = print("<ol>" + correctAnswers + "</ol>");

//Wrong Answers
print("<h2>You got these questions wrong:</h2>");
var wrongList = print("<ol>" + wrongAnswers + "</ol>");

The code does meet the objectives.

Firstly, a technical question -- why is it that I am assigning an empty value to some of the variables. I only did so, as testing revealed that the browser would render "undefined" onto the page without an empty value of "". I am not too clear as to when I have to assign an empty value when creating variables.

I have tried thinking through that, realized that couldn't I just created all variables right from the start with = " ". Even if I didn't, I am rule-bound to test my code, and any undefined errors would then get fixed.

I guess what I do want to know, is whether there is a more intuitive way to know when I have to assign = " " right from the start. Hopefully you all have some insight.

Next question, then would be more about the approach to take when coding JS.

After comparing the instructor's solution to my own, I just didn't know whether I can feel as though my solution is acceptable. I felt that I had a pretty clear sense during the coding as to why I was writing it the way I did. Even discounting the bias that I wrote it, I felt I had a easier time digesting my version over the instructor's.

So it just bothered me, that I was not using more "fancier" stuff I'm being taught to complete the challenge. And that it didn't just intuitively occur to me like, "Hey, I need a new function here". Or the .push() method etc.

To sum it up, I feel that maybe my code is too simplistic or non-optimal. Could someone maybe explain the intuitive reason the instructor had when creating the other function. Hopefully something in my mind can click after hearing new reasoning.

Thank you for your time. Cheers.