What is defined as items shipboard or approved by fleet commanders for special inventory control?

The correct response is equipage. This term specifically refers to certain items on ships or those authorized by fleet commanders that require special inventory control due to their operational importance or specific use on board. Equipage often includes tools, gear, or supplies that are critical for mission readiness, making their tracking and management essential for efficient naval operations.

In this context, other terms have different meanings. Supplies generally refer to all kinds of resources available on a ship, including consumables and provisions, not specifically requiring special inventory management. Inventory is a broader term that encompasses all listed items and materials but does not imply the specialized control that equipage does. Equipment usually refers to tools or machinery used for a specific purpose but does not carry the same connotation of special oversight or restrictions that equipage denotes. Thus, equipage is the most accurate term for items requiring discrete inventory control as defined in the question.