Answer:
C). It is a relative clause describing the qualities of the brownies.
Step-by-step explanation:
Relative clause is illustrated as the subordinate or dependent clause usually begin with a relative pronoun like who, when, where, etc. and primarily functions to describe or modify the noun stated before it.
In the given statement, the underlined clause 'which were chewy, chocolatey, and jam-packed with crunchy walnuts' would be characterized as the 'relative clause' that describes the 'qualities of noun brownies' mentioned before it in the principal clause. It justifies the above definition appropriately as it begins with the relative pronoun 'which' and dependent on the independent or principal clause 'Sami especially enjoyed the brownies' to accomplish its meaning. Thus, option C is the correct answer.