Where others maybe harsh in responding this really is something that you need to research not ask here.

There is a safe harbor rule and other resources that you can easily find to help make this determination but I think it is a determination that you and your client need to make.

It is the clients responsibility to keep documentation to prove that the rental is being operated as a business if the deduction is taken.

I have heard preparers say that rentals do not qualify.  I think that may come from they don't want to do the work to try to prove they do qualify.