It's perfectly fine, at your age to not answer a question.
My parents want to rule my life (still!) and I have been in the situation of evading and evading to no avail (they don't understand subtle). Finally I have had to be blunt and say "it really is none of your business". Because it's not.

Have boundaries in your life. Then, as googley said, your parents can choose to have some relationship, or no relationship with you depending on if they respect those boundaries.