Ablank clause should always be separated from the rest of the sentence by commas

Independent clause uses commas to separate independent clauses when they are joined by any of these seven coordinating conjunctions: and, but, for, or, nor, so, yet.

Relative clause- makes additional comment or information about the referring noun is separated by a comma.

Carol, who wanted to go swimming, was stuck in traffic

are there answer choices to this particular question?

pulling in the reader is important