It's not a trade or business, because you do not provide recurring services that are exclusive to and directly benificial to the tenant. Examples would include things like preparing meals, house cleaning services, or other services provided or the tenants on a constant (usually recurring) basis.
Normal maintenance (such as fixing things reported broken, and weekly yard care) don't count for that, because these are things are done weather or not a tenant is in the property. Oh, I am also assuming that all rentals are long term rentals, and not short term rentals such as one deals with on VRBO or AirB&B. The latter are without question, a SCH C rental.
So if only one of your rentals is short term, then only that rental is a SCH C business. The other rentals, if long term are SCH E, unless you provide services to all of those tenants that are directly benificial to those tenants.
