At what point can the RAT be deployed?

The correct answer is that the RAT (Ram Air Turbine) can be deployed at any speed within the aircraft's operating envelope. This is significant because the RAT is designed to provide emergency power to critical systems during an in-flight failure of the main electrical power sources. The ability to deploy it at any speed allows for operational flexibility and prepares the aircraft to handle various emergency scenarios, regardless of altitude or airspeed.

While it may seem intuitive to limit the deployment of the RAT to emergencies or lower altitudes—perhaps due to concerns about performance or stability—the primary design of the RAT is to function effectively throughout the aircraft's operational range. This ensures that pilots can quickly and decisively respond to power loss, providing necessary hydraulic pressure and electrical power, which is crucial for maintaining control of the aircraft.

In contrast, the other choices suggest unnecessary limitations on the deployment of the RAT. It is intentionally designed for use in a wide range of conditions to ensure that pilots are equipped to manage emergencies effectively, safeguarding both the aircraft and its occupants.