Answer:Which sentence uses commas correctly to set off a nonrestrictive clause?
C. I had to fix my bike, which I bought less than a year ago.
Explanation: The answer is C. I had to fix my bike, which I bought less than a year ago because it is the only sentence that uses commas correctly and is the only option that is grammatically accurate. A nonrestrictive clause contains extraneous information that would not affect the meaning of the sentence.