Chose #4.  Ask them why they want to know if you've had a flu shot.  If they say that it would interfere with something they might give you, then there would be a legitimate reason why they would need to know.  This is extremely unlikely with regard to the flu shot, but maybe not for other things.  If they say that they want to give it to you "for your own good," then you need it in writing that you are declining that "service." Also, take advice from above and always read the forms they give you, change them as needed, and only then sign.