He is the correct answer.
Remeber that in any sentence, the person or thing that is doing the action or being described is the subject. Each verb must have one subject, in this case the verb is painted, so we can ask: Who or what painted? He is the only possible answer. A subject can't be part of a prepositional phrase.
A complete subject is formed by the person or thing doing the verb plus the modifiers. In this case, there are no modifiers.
