What is needed to open or close the cargo doors besides manual locking and unlocking?

To open or close the cargo doors of the A320, hydraulic pressure is required in addition to manual locking and unlocking. The cargo door mechanism is designed such that hydraulic actuators power the movement of the doors, enabling them to open and close smoothly and securely. The hydraulic system provides the necessary force to operate the door mechanisms under normal operating conditions, ensuring that the doors function effectively and can be sealed tightly against the aircraft structure to maintain pressurization and safety during flight.

While other options may involve different systems or components, they are not primarily responsible for the operation of the cargo doors. For instance, electric power might be involved in controlling the hydraulic system, and mechanical force could be applied for manual operations, but the primary requirement for moving the cargo doors is hydraulic pressure.