Quiz

Ok I answered my own question. You just need to overwrite the quiz renderer.

Here is what I did:

In my theme, I create a file:

/theme/mytheme/renderers.php

Then add the following code in the file:

<?php

include_once($CFG->dirroot . "/mod/quiz/renderer.php");

class theme_themenamehere_mod_quiz_renderer extends mod_quiz_renderer {

public function review_page(quiz_attempt $attemptobj, $slots, $page, $showall, $lastpage, mod_quiz_display_options $displayoptions, $summarydata) {
        // Number of allowed attempt for the quiz
        $allowedAttempt = $attemptobj->get_num_attempts_allowed();

        // current attempt #
        $currentAttempt = $attemptobj->get_attempt_number();

        // Display the correct answer if the current attempt # equal the total allowed attempt

        if ($allowedAttempt == $currentAttempt) {
            $displayoptions->rightanswer = 1;
        } else {
            $displayoptions->rightanswer = 0;
        }

        return parent::review_page($attemptobj, $slots, $page, $showall, $lastpage, $displayoptions, $summarydata);
}

Any suggestion are welcome