One of the restrictions on the site I use is that the images cannot be posted "online in a downloadable format"

Technically though, any image displayed in a browser can be downloaded by various means and methods. So what steps should I take to make it allowable? Is it ok if I:

a. Display the image as CSS background?
b. Disable right clicking?
c. Use htaccess to disallow hotlinking
d. Just post the picture as long as I don't have a "download this picture" script for it.

The terms aren't very clear and I'd like to avoid repercussions. Thanks.