Which type of unit type codes information includes primary mission aircraft inventory?

The correct choice is based on the understanding that unit type codes (UTCs) are used to report and categorize the capabilities of forces. The primary mission aircraft inventory refers to the specific aircraft that a unit is responsible for operating, which directly correlates to aviation functions within the military context.

Aviation UTCs provide detailed information about the units' operational capabilities, including the types and quantities of aircraft available for deployment and missions. This ensures that planners can effectively utilize these assets for various missions and align resources with operational needs. Therefore, since aviation is focused on the management and operational readiness of aircraft, this option correctly represents the type of information that includes primary mission aircraft inventory.