You were right Iceman - it was Bobby.
I believe that is short for Roberta.
Boca would have been a whole different episode if Bobby had turned out to be a guy.

To answer your question.
A. Paulie and Christopher killed Mickey Palmice.

New Question:

When Jackie Aprile died - Tony still didn't want to be Acting Boss - but was not keen on Junior. getting the big chair.

Who did Tony want to go for the top job instead?

A. Larry Boy Barese
B. Jimmy Altierei
C. Raymond Curto
D. Paulie Gualteri
E. Junior Soprano
F. Richie Aprile