Possible to set the captcha image to just one certain image?

It is not possible with Really Simple CAPTCHA plugin.

Thanks for your quick reply! Much appreciated. I am open do ideas. I need to have a text field verify for a specific word (IE: giveaway)and only allow submission if that is the entry in that text field. How would I best do this?

I am using Contact Form 7, btw

You should open a new topic for another question though, maybe using quiz?