Which theater air control system unit is capable of data link operations but lacks inherent surveillance radar capabilities?

The Air Operations Center is the correct answer because it functions primarily as a command and control entity responsible for managing and directing air operations within a specific theater. While it has the capability to coordinate and manage data link operations, it does not possess its own inherent surveillance radar capabilities. Instead, it relies on other units for real-time surveillance and tracking data.

The Aerial Operations Center and Combat Operations Center, on the other hand, generally have more integrated capabilities for surveillance and tracking within their operational frameworks, often utilizing various radar systems and networks. Similarly, the Forward Air Control Unit is specifically designed for directing air support in close proximity to ground forces and typically includes some surveillance function to ensure the safety and coordination of air strikes. Thus, the limitations of the Air Operations Center regarding surveillance radar capabilities make it the correct choice in this context.