What information does Mode C of IFF provide?

Mode C of Identification Friend or Foe (IFF) provides the altitude of the aircraft. This mode is part of the overall IFF system, which is designed to enable radar systems to distinguish between friendly and hostile entities in the airspace. By using Mode C, ground-based or airborne radar can receive altitude information transmitted from an aircraft's transponder, allowing for a clearer understanding of the aircraft's position and operational status.

Altitude data is crucial in air traffic control and military operations to ensure safe airspace management and to prevent mid-air collisions. Knowing the altitude helps controllers and other aircraft maintain safe vertical separation. In military contexts, it can also assist in situational awareness and tactical maneuvering.

The other options relate to different types of information that are not provided by Mode C: target distance is typically associated with other radar functions, the direction of submarines would not be part of an IFF system focused on aerial operations, and tactical commands are communicated through different channels and not through IFF transponders.