Which of the following generates supervisory signals?

The generation of supervisory signals is an important function in fire alarm systems, primarily for monitoring and ensuring the operational readiness of other critical components within a fire protection system. The valve supervisory switch on a sprinkler system is designed to monitor the position of control valves. When a valve is closed or opened improperly, the supervisory switch activates, sending a signal to the fire alarm system to indicate this condition. This helps ensure that the sprinkler system is functional and ready to operate in the event of a fire.

In contrast, smoke detectors are primarily designed to detect the presence of smoke and trigger alarm signals rather than supervisory signals. Fire extinguishers, while vital for fire suppression, do not typically generate supervisory signals as they serve a different purpose in fire protection. Similarly, manual pull stations are intended for initiating an alarm in case of fire but do not provide supervisory functions related to system integrity or readiness. Thus, the valve supervisory switch's role in monitoring valve status makes it the correct choice for generating supervisory signals within a fire alarm system.