What does the term 'C-Day' refer to?

The term 'C-Day' specifically refers to the day when a deployment operation officially commences. It serves as a critical reference point in planning and executing military operations, marking the transition from preparation to active deployment. This ensures all involved parties are aligned regarding the timeline and actions required as the operation begins. The designation of such a day helps to streamline coordination among various units and support services, establishing a clear timeline that allows for efficient management and strategic execution.

In contrast, the other options relate to different aspects of military operations but do not capture the definition of 'C-Day' as accurately. Tactical operations, logistical resource allocation, and troop arrival, while important, are not designated by the term 'C-Day.'