What system primarily supports large-scale, geographically distributed control systems?

The correct answer is based on the primary role and functionality of Supervisory Control and Data Acquisition (SCADA) systems in managing large-scale and geographically distributed control systems. SCADA is designed to monitor and control industrial processes and infrastructure in various sectors, such as water treatment, energy, and transportation.

SCADA systems allow for centralized control of multiple distant sites and provide operators with real-time data collection, monitoring, and command capabilities. This is critical for functions that require coordinated operation across various locations, enabling effective management and oversight of processes that span large geographic areas.

The other options, while related to industrial automation and control, do not fulfill the same broad role as SCADA. Fieldbus refers to a communications network and protocol for field devices, rather than a system for large-scale control. A Data Historian is designed primarily for collecting and storing process data over time, which is integral to analysis but does not perform control functions. The Human-Machine Interface (HMI) serves as a user interface by which operators interact with the SCADA system but does not encompass the full capabilities of monitoring and controlling distributed systems. Thus, SCADA stands out as the system that primarily supports these expansive and complex control environments.