The sentence in which an essential appositive or appositive phrase is underlined is option C.
Charlottes web, a novel by E.B. White, portrays the powerful friendship between Wilbur and Charlotte.
An appositive is a noun or noun phrase that renames another noun placed right beside it in the sentence. The appositive can be a short or long combination of words. An appositive is always separated from the rest of the sentence with commas.