What areas does the main drainage system cover?

The correct answer highlights the specific areas involved in a ship's main drainage system. The main drainage system primarily covers the Forward Main Machinery Room (FWD MMR), Aft Main Machinery Room (AFT MMR), Auxiliary Machinery Room (AMR), and Shaft Alleys. Each of these locations plays a crucial role in managing water ingress and ensuring the vessel's stability and safety.

The Forward and Aft Main Machinery Rooms house essential machinery and systems; hence, they require effective drainage to prevent any flooding that could compromise the equipment or the vessel's seaworthiness. The Auxiliary Machinery Room typically supports functions related to the main propulsion and other vital systems, making its drainage equally important. Shaft Alleys provide passage for the propulsion shafts and may experience water collection from various sources, so efficient drainage is vital here as well.

This thorough coverage is essential for maintaining operational integrity and safety at sea. The other options do not include all the critical areas covered by the main drainage system—some refer to areas that are not primarily involved in drainage, potentially leading to confusion about the specific responsibilities of shipboard drainage systems.