updated-login-question.php

<?php
function rkv_login_stringcheck()
{
  global $pagenow;
	if ( $pagenow == 'wp-login.php' )
	{
		// set the location a failed attempt goes to
		$redirect = 'http://www.google.com/';
 
		// missing query string all together
		if (!isset ($_GET['question']) )
			wp_redirect( esc_url_raw ($redirect), 302 );
 
		// incorrect value for query string
		if ($_GET['question'] !== 'answer' )
			wp_redirect( esc_url_raw ($redirect), 302 );
	}
}
add_action( 'init', 'rkv_login_stringcheck' );