Question

is the group of words in bold a phrase or a clause? built to honor all the gods, the pantheon is a monument that is an exceptional example of ancient roman architecture. phrase clause

Explanation:

A clause contains a subject and a predicate (a verb or verb phrase). The bolded group "that is an exceptional example of ancient Roman architecture" has the subject "that" and the predicate "is an exceptional example...", so it's a clause. A phrase lacks a subject - predicate structure.

Answer:

clause