What must be restored to normal after activation of a pressure tank signaling device?

The correct answer is that pressure must be restored to normal after the activation of a pressure tank signaling device. This is crucial because pressure tanks are designed to hold fluids under a specific pressure to ensure proper functioning of the system, whether it's for water supply, heating, or industrial processes.

When a signaling device is activated, it typically indicates that the pressure within the tank has fallen below or risen above predetermined levels. Restoring the pressure to normal ensures that the system can operate efficiently and safely. If the pressure remains outside the normal range, it could lead to system inefficiencies, equipment failures, or even safety hazards.

Restoring temperature, flow rate, or voltage might be important in certain contexts, but in the case of a pressure tank signaling device, the primary concern relates to pressure levels and their impact on the overall system performance.