How to add "Select an option" line before the options?

Hi guys. Right to the point. I had a downloadable product with two options (A and B). Many customer just click add to the cart and buy (A) without to see that there is another option. So then they write me asking "I',m sorry can you send me the option B? I didn't realize that it was. That is because the Zen cart Select the first one by default. But I want to have a "Select an option" line in the list before the options. So in that way is the customer add it they should receive a error message saying something like "Please choose an option before to add to the cart".

There is any way to do this? Thanks in advance!

The standard method for requiring a customer choice on attributes is to create another option value for the option name, calling it "Please Choose" or whatever you want, and add that as an attribute to the product along with the "real" ones. Make this Default and Display Only, and it will not allow adding to cart until another value is selected.

Thank you so much buddy!! You made my day! LOL.