You didn't italize or mark the phrase, but I see one good candidate:
"The circus animal trainer" is in a way another name given to Mervin, a kind of "renaming" him: this is called an appositive phrase, so if this was the phrase appositive phrase is the answer! (also, I don't see the other phrases here).
Being the italicized phrase "the circus animal trainer," the correct option is appositive.
This phrase refers to and modify the noun that preceeds it. In this case it renames the noun MERVIN.
An appositive is defined as a noun or noun phrase that renames another noun right beside it. The appositive can be a short or long combination of words. It is alway placed in the sentence between commas in order to separate it from the rest of the sentece.
