Identify the correctly punctuated sentence.
- A. My brother who lives in Karachi is a doctor.
- B. My brother, who lives in Karachi, is a doctor.
- C. My brother who lives in Karachi, is a doctor.
- D. My brother, who lives in Karachi is a doctor.
Explanation
A non defining relative clause, one that adds extra information rather than identifying which brother, is enclosed by a pair of commas. Using only one comma is always wrong, since the pair works like brackets. Without commas the clause would be defining, implying the speaker has more than one brother.