Conversation so far:
how many bureaucrats work for the us government
There are over 2.7 million bureaucrats working for the government.
In what departments do the bureaucrats work for the US government
The bureaucrats work in six big agencies- Departments of the Army, Navy and Air Force, VeteransAffairs, Homeland Security and the Postal Service.

Question: Which one is the largest
Self-contained rewrite: Which department of the government bureaucratic jobs is the largest