Options for products

I sell ebooks on my site that come in 3 different formats. How can I set up my store so that when a customer chooses one of the options (e.g., PDF) only that file (and not all 3 file types) is available for download to him after checkout?

Do I need to create a product for each of the file types or would options work?

Thanks.

Nevermind, I figured it out.