Which component serves as a backup control for the elevators?

The backup control for the elevators on the A320 is provided by the SECs, or Spoiler Elevator Controllers. These components play a critical role in maintaining control of the aircraft's pitch when the primary elevator control system is not functioning properly. The SECs can utilize spoilers in conjunction with the elevators to assist in controlling the aircraft's attitude and improve overall maneuverability and stability.

When the elevators are ineffective due to a malfunction, the SECs come into play by activating the spoilers to generate a downward force on the wings, which helps to adjust the aircraft's pitch. This system allows for continued control of the aircraft, ensuring safety and reliability even in the event of primary control system failures.

The other components listed do not serve the function of providing backup control for the elevators. Rudders, stabilizers, and flaps have roles primarily in controlling yaw, providing stability, and increasing lift, respectively, but do not specifically act as a backup for elevator control. The SECs are uniquely designed for this purpose, underscoring their importance in the aircraft's control architecture.