Which mission letter corresponds to the transport category?

The mission letter that corresponds to the transport category is the one that identifies the specific operational context for aircraft designated for transporting personnel or cargo. In this case, mission letter C is the correct answer as it is generally used to denote transport missions, distinguishing these aircraft operations from those designated for different purposes such as reconnaissance or attack.

Transport missions focus on the efficient movement of goods and personnel, which is a critical function of military aviation. By identifying this operational category with a specific letter, it allows for standardized communication and categorization within mission planning and execution.

The other options correspond to different mission types, including specialized operations or support roles, rather than transport, which reinforces the importance of understanding the role that each letter designates in mission planning.