Question

is the group of words in bold a phrase or a clause?
crayfish are often associated with water, but the prairie crayfish can be found in pastures, where they live in underground burrows.
phrase clause

Explanation:

A clause has a subject and a predicate (verb). The bolded group "Crayfish are often associated with water" has the subject "Crayfish" and the predicate "are often associated with water" (containing the verb "are"). A phrase lacks a subject - predicate structure. So it's a clause.

Answer:

clause