Code review and toLowerCase() on Arrays?

function print(message) {
  document.write(message);
}
var qa = [ 
    ['Who directed Full Metal Jacket, Eyes Wide Shut & 2001: A Space Odyssey?', 'Kubrick'],
    ['Who directed Rear Window, The 39 Steps and Marnie?', 'Hitchcock'],
    ['Who directed Through A Glass Darkly, Seventh Seal and Persona?', 'Bergman']
];
var correctQuestions = [];
var incorrectQuestions = [];


function askQuestion() {
  for (var i = 0; i < qa.length; i++) {
      answer = prompt(qa[i][0]);
      // answer = answer.toLowerCase();
      if (answer === qa[i][1]) {
        alert("Correct!");
        correctQuestions.push(qa[i][0]);
      } else {
        alert("Incorrect!");
        incorrectQuestions.push(qa[i][0]);
      }
  }
}

askQuestion()

print('<h1> Your score is ' + correctQuestions.length + '.</h1><br><h2>You got these questions correct:</h2>' + correctQuestions.join('<br>'));
print('<h2>You got these questions correct incorrect:</h2>' + incorrectQuestions.join('<br>'));

answer = prompt(qa[i][0]).toLowerCase;

answer = prompt(qa[i][0]);
answer = answer.toLowerCase();