Parent's residence? Confused as to what to put.

My father owns a business in a different state. It requires lots of his attention, therefore he is often in that state. He rents an apartment and stays there approximately 2-3 weeks out of the month. He and my mom are still together, though. They are not separated, this is just for work.
Do I put his residence as my home address, or the apartment he rents?
So confused. Thanks.

Put the state of residence where you live with your parents.