The correct answer is, D. It will follow a general noun and is not set
off by commas. A restrictive adjectival clause (also called essential
clause) is essential to the meaning of sentence because it refers to
specific noun in sentence. Deleting this clause will change the meaning
of the sentence. Since these are essential, the are not set off by
commas. E.g. All students who have scored more than 80 percent will move
to next round.
