If a fuel imbalance is detected by the ___________ of 20 pounds or more for more than 30 seconds, the appropriate transfer (solenoid) valve is activated to close the motive flow line to the lighter tank.

The Engine Data Manager (EDM) is responsible for monitoring various parameters related to engine performance and aircraft systems, including fuel management. When a fuel imbalance of 20 pounds or more is detected for a duration exceeding 30 seconds, the EDM plays a critical role in triggering the corrective action necessary to address this imbalance. It activates the appropriate transfer valve, which subsequently closes the motive flow line to the lighter tank. This process ensures that the fuel distribution is balanced and helps maintain optimal performance and safety during flight.

The other choices do not fit this specific function. The Fuel Management Unit (FMU) primarily handles fuel flow and management but does not manage the imbalance detection criteria in the same way as the EDM. The Power Management Unit (PMU) is focused on regulating engine power settings and performance parameters, while the Fuel Data Manager (FDM) also deals with fuel data but typically does not perform the real-time monitoring and corrective action for imbalances. Therefore, the EDM is the correct choice for this scenario.