Which sentence correctly uses a nonrestrictive clause with commas?

Which sentence correctly uses a nonrestrictive clause with commas?

• A. The scientist who discovered the anomaly won an award.
• B. The scientist, who discovered the anomaly, won an award.
• C. The scientist, who discovered the anomaly won an award.
• D. The scientist who discovered the anomaly, won an award.

Answer: (B)

Nonrestrictive clauses add extra information about a noun and are set off by commas. Here, the phrase “who discovered the anomaly” is additional detail about the scientist and does not change which scientist is being talked about—it can be removed without altering the main idea: the scientist won an award.

Because this information is nonessential, it’s enclosed in commas: The scientist, who discovered the anomaly, won an award. If you drop the extra clause, you still have a clear statement: The scientist won an award.

The other options either treat the clause as essential information (restrictive, with no commas), or place punctuation incorrectly, which breaks the flow or meaning. Using a restrictive clause signals there are multiple scientists and only the one who discovered the anomaly won an award; that’s not the nonrestrictive construction shown here. Misplacing or missing the closing comma around the nonrestrictive clause also disrupts the punctuation rule.