Final answer:
The bolded word group is a clause because it contains both a subject ('which') and a predicate ('are known').
Step-by-step explanation:
The bolded word group in the sentence “Frankfurters, which are also known as wieners or hot dogs, originated in Frankfurt, Germany, and are traditionally made from pork and beef.” is a clause. To understand why it is a clause rather than a phrase, we should consider the definition of both terms.
A phrase is a group of words that act as a single part of speech but do not contain both a subject and a verb. A clause, on the other hand, is a group of words that includes a subject and a predicate.
The word group “which are also known as wieners or hot dogs” contains the subject “which” and the verb “are known,” making it a clause and more specifically, a relative clause that provides additional information about the noun 'Frankfurters'.