A (n) clause should always be separated from the rest of the sentence by commas.

dependent

independent

c nonrestrictive

d. restrictive

A clause that is always be separated from the rest of the sentence by commas is called dependent clause. It’s a type of clause that cannot stand alone in a sentence, so they need to be combined with another clause e. g. main clause or independent clause. Because this clause can’t stand alone, it is always separated by commas.

The awnser is C.) Nonrestrictive