$('.reg_field_qualification_div').hide();
$('#FieldInterestedIn').change(function () {
            if ($('#FieldInterestedIn').val() == '320404' && $('#FieldInterestedIn').val() != '' && $('#FieldInterestedIn').val() != undefined) {
                $('.reg_field_qualification_div').show();
            }else{
                $('.reg_field_qualification_div').hide();
            }
        });