Before an analog controller can react, digital output signals must be processed by what?

The correct choice highlights the role of analog converters in the functionality of analog controllers. In systems where digital signals are generated, they typically need to be transformed into analog signals for the analog controller to effectively manage processes or equipment. Analog converters, often referred to as Digital-to-Analog Converters (DACs), serve as the interface that translates the digital output signals into a format that can be understood and acted upon by the analog control mechanism.

This conversion is crucial because analog controllers operate on varying levels of signals rather than discrete digital values. For instance, if a temperature setting needs to be adjusted or a pressure control system is designed to maintain a specific level, the analog controller must receive continuous variable signals that reflect these parameters. The DAC performs this essential function, allowing for more nuanced control in comparison to strictly digital systems.

The other options, although involved in system control and processing, do not specifically address the necessity of converting digital signals to an analog format for the controller to react appropriately. Therefore, recognizing the essential role of analog converters in this context is key to understanding how cooperation between digital systems and analog control mechanisms is achieved in refrigeration and other relevant applications.