C. I am reading a biography of Christopher Reeve the actor in the original Superman movies.
The appositive in the given sentence: J.M. Barrie's book Peter Pan was made into a play and a movie, isĀ (a) J.M. Barrie's book. Appositives are noun or noun phrases which gives another name to the noun near it. They are very easy to trace. In this case, Peter Pan is a noun. It is renamed into J.M. Barrie's book. Thus, "Barrie's book" is an appositive of Peter Pan.
Additional Notes:
(b) was made: is the verb
(c) Peter Pan: is the main noun
(d) into a movie: is the prepositional phrase