jQuery show/hide a div based on select value

You can clean up the HTML by dropping the onClick and removing the IDs from the options.

HTML:

<div>
    <label>Privileges:</label>
    <select name="privileges" id="privileges">
        <option value="all">All</option>
        <option value="custom">Custom</option>
    </select>
</div>
<div class="resources" style=" display: none;">resources</div> 

And your JavaScript could simply do this:

$('#privileges').on('change', function() {
        if($(this).val() === 'all') {
            $('.resources').hide();
        } else {
            $('.resources').show();
        }
 });

You need to use val method:

var Privileges = jQuery('#privileges');
var select = this.value;
Privileges.change(function () {
    if ($(this).val() == 'custom') {
        $('.resources').show();
    }
    else $('.resources').hide(); // hide div if value is not "custom"
});

http://jsfiddle.net/RWUdb/