What unit displays status information about a circuit or condition?

The correct choice is the annunciator, which is designed specifically to display status information regarding various circuits or conditions within a building's system. An annunciator panel typically provides visual indicators such as lights or displays that show whether certain systems are functioning properly or if there are any alarms or alerts that require attention.

For example, an annunciator can indicate the status of fire safety systems, security systems, or HVAC conditions by showing whether a particular area is experiencing a fault or if it is functioning within normal parameters. This enables quick response and awareness for building management and safety personnel.

Other options, while important in their respective functions, do not primarily serve as status display units. Audible alarm notification appliances are focused on alerting occupants through sound; automatic smoke detection systems are focused on detecting smoke and triggering alarms; and automatic sprinkler systems are designed to extinguish fires. None of these options offer the comprehensive status information display capability of an annunciator.