Question

Support staff in the office of the president include

Answer 1

Well, support staff in the office of the president includes all of these - administrators, cabinet members, reporters, and party leaders, but I guess that if you had to choose only one option, I'd also go with 1. administrators. 

Answer 2

Support staff in the office of the president include administrators.

Explanation:

The President is that the chief administrator of the centralized government. He's accountable for all federal departments, together with cabinet departments, like the State Department, and other agencies.
The EOP supports the work of the President. They can be the members of White House Office, National Security Council or Office of Management and Budget. Some of them report directly to the president and some indirectly.