help can't hide an object

help can't hide an object

Hi,

I'm trying to hide an object if the dropdown did not select the first object, but it won't work
where did I do wrong?

This is my code:
  1. if $('select option:first)')
  2. .is('not(:selected)')
  3. {
  4.     $('.attachment').hide();
  5. } 

Thanks!