Question

complete the sentence. the best resource for locating a synonym of vestiges as used in paragraph 4 would be a dropdown with options: dictionary, thesaurus, glossary, index

Explanation:

A thesaurus is a resource specifically designed to provide synonyms (and antonyms) of words. A dictionary primarily gives definitions, a glossary defines terms specific to a subject, and an index helps locate information in a book. So to find a synonym for "vestiges", a thesaurus is the best choice.

Answer:

thesaurus