A subject complement is either a adjective, a noun, or a pronoun that follows a linking verb.
Welp, the kid appears to have pawned his work off on his friends, but who knows, if it's a multi-choice question I can't really help because you don't have the answers here.
If you are sure that A and D are not the answers, and if you are that there are three correct answers, then logically the correct answers are B,C, and E.
Have a good day :)