get_option for Thumbnail Alignment

I am attempting to align my thumbnail images based on the settings chosen on the edit post screen. From what I read on this page it seems like I need to use the get_option tag to figure out what alignment is being used. This is what I think needs to be done (I am a rather inexperienced coder)

$a = get_option('thumbnail_align') / 2;

the_post_thumbnail(array(100, 100), array('class' => 'align$a'));

The problem is that get_option(‘thumbnail_align’) (as far as I know) isn’t valid. The current documentation on get_option doesn’t mention anything about thumbnails. Anyone have any ideas?