Which sentence correctly uses a nonrestrictive clause with commas?

• A. The policy, which was controversial, passed.
• B. The policy which was controversial passed.
• C. The policy, which controversial was passed.
• D. The policy, which was controversial, passing.

Answer: (A)

Nonrestrictive relative clauses add information that can be left out without changing who or what is being talked about, and they are set off with commas. In this sentence, the clause “which was controversial” describes the policy but isn’t needed to identify the policy itself—the main idea is that the policy passed. Framing that extra detail with commas shows it’s supplementary information, so the sentence reads smoothly as: The policy, which was controversial, passed.

If you left out the commas, the clause wouldn’t be presented as optional extra information, which would shift the meaning or make the sentence awkward. The other forms either misuse the punctuation, create an incorrect or unclear structure, or turn the clause into a nonessential modifier in a way that disrupts the flow.