The correct answer is C. I bought a book, an atlas of famous caves.
Appositives and appositive phrases are used to describe subjects and direct objects. They are usually separated from the rest of the sentence using commas.
A is incorrect because the appositive <em>a windbreaker </em>is renaming the subject <em>my jacket</em>; B is incorrect because the appositive phrase <em>a historic explorer </em>is renaming the predicate nominative <em>an archaeologist; </em>D is incorrect because the appositive phrase <em>the name of a famous operatic tenor </em>is renaming object complement rather than the direct object.
This leaves us with sentence C - here, the noun <em>a book </em>is a direct object, and the appositive phrase <em>an atlas of famous caves </em>renames it.