add anti-spam functions in the contact form

Hi, I am using the Enfold contact form , to keep away from the spam email attacks though contact form
so to ask the email sender to answer one question to make the submit successful might be helping

Can you check if this code is working? to the functions.php

add_action( ‘contact_form’, ‘add_security_question’ );
function add_security_question() { ?>
<p>
<label><?php _e(‘Washington D.C is the capital of USA’) ?><br />
<input type=”text” name=”user_proof” id=”user_proof” class=”input” size=”20″ tabindex=”20″ /></label>
</p>
<?php }

add_action( ‘contact_post’, ‘add_security_question_validate’, 10, 3 );
function add_security_question_validate( $sanitized_user_login, $user_email, $errors) {
// if do not answer
if (!isset($_POST[ ‘user_proof’ ]) || empty($_POST[ ‘user_proof’ ])) {
return $errors->add( ‘proofempty’, ‘wrong: you forgot to answer my question’ );
// If answer was wrong
} elseif ( strtolower( $_POST[ ‘user_proof’ ] ) != ‘Yes’ ) {
return $errors->add( ‘prooffail’, ‘Yes: Wrong answer’ );
}
}

Can you check my contact page and help me to correct this codes?

This is the codes to prevent robot registry, I think IT should help in robot spam emails..