The correct answer is D) automatically hold the load if power to the winch motor is disconnected. The electric brake on a deck cargo winch is designed to automatically engage and hold the load in place if the power supply to the winch motor is interrupted or disconnected. This is a critical safety feature to prevent the load from suddenly dropping or lowering in an uncontrolled manner, which could be dangerous. The other options are incorrect because the electric brake does not automatically govern the hoisting or lowering speed (A and B), nor does it engage based on the winch motor current reaching full load (C). The primary function of the electric brake is to provide a fail-safe mechanism to secure the load in the event of a power failure or interruption.