Question

what is the best definition of an appositive?
a nonrestrictive phrase that modifies a noun
a clause that modifies or explains a noun
a noun or noun phrase that modifies a noun
a noun clause that restricts the meaning of a noun

Explanation:

An appositive is a grammatical element that is always a noun or noun phrase, placed next to another noun to rename, identify, or explain it. It can be restrictive or nonrestrictive, so options limiting it to nonrestrictive phrases, clauses, or noun clauses are incorrect.

Answer:

a noun or noun phrase that modifies a noun