Identify the correct punctuation for a sentence containing a non-restrictive clause.

1. ক
   My brother who lives in Dhaka is a doctor.
   
2. খ
   My brother, who lives in Dhaka, is a doctor.
   
3. গ
   My brother who lives in Dhaka, is a doctor.
   
4. ঘ
   My brother, who lives in Dhaka is a doctor.