Challenge Quiz Help

var question_1 = prompt("What is stressed spelled backwards?").toLowerCase();
var question_2 = prompt("What Seseame Street character lives in a trash can?").toLowerCase();
var question_3 = prompt("What is 12 x 12?");
var question_4 = prompt("How fast is a porsche?").toLocaleLowerCase();
var question_5 = prompt("What element attack is pikachu?").toLowerCase();
var score = 0;
if ( question_1 === "desserts" ) {
  score += 1;
  console.log(score);
} if ( question_2 === "oscar" ) {
    score += 1;
    console.log(score);
} if ( question_3 === "144" ) {
  score += 1;
  console.log(score);
} if ( question_4 === "fast" ) {
  score += 1;
  console.log(score);
} if ( question_5 === "lightening" ) {
  score += 1;
  console.log(score);
} if ( score = 5 ) {
  document.write("<p>Wow, a perfect Score.  You get a gold</p>" + "Score: " + score); 
} else if ( score = 4 ) {
  document.write("<p>Great job, you earned a silver</p>");
} else if ( score = 3 ) {
  document.write("<p>Great job, you earned a bronze</p>")
} else document.write("<p>Nice try, please try again to get a medal!</p>")