Have they asked for the Principal Applicant’s (your) proof of citizenship or your husband’s? (Sponsor). You said your country of birth is India so what’s your status in the USA?
Its weird that your file was transferred to Los Angeles VO because usually they send the application at PA’s country of birth even if you live in another country. If they are asking for your proof of citizenship, and if you are born after July 1 1987, then just your passport copy wont suffice as proof. The law states that one or both of your parents should be Indian citizens at time of birth. So I think sending them your birth certificate (even if you did send that before) along with your parents’ birth certificates can be used to prove your Indian Citizenship. Please refer to the following link.