Final answer:
The underlined word "a symbol of San Francisco" is a predicate nominative.
Step-by-step explanation:
In the given sentence, the underlined word "a symbol of San Francisco" is a predicate nominative. A predicate nominative renames or identifies the subject of a sentence. In this case, the subject is "The Golden Gate Bridge" and the predicate nominative "a symbol of San Francisco" identifies or renames the subject.
Learn more about Identifying grammatical elements in a sentence