Detailed Solution:
The correct answer is “Speaker of the Lok Sabha”.
The Lok Sabha Secretariat is under the direct control of the Lok Sabha Speaker. The Speaker's authority over the Secretariat's security, staff, and precincts is supreme. The Speaker is assisted by the Secretary-General of the Lok Sabha, who serves as the Secretariat's administrative head.
The Secretary-General is only accountable to the Speaker and can't be criticized or have their actions discussed inside or outside of the Lok Sabha.