Which components make up the fixed surfaces of an empennage?

The fixed surfaces of an empennage are comprised of the vertical and horizontal stabilizers. These structures provide essential stability to the aircraft during flight.

The horizontal stabilizer prevents undesirable pitching motions by providing a counteracting force to the aircraft's nose, while the vertical stabilizer helps maintain directional stability, preventing side-to-side oscillations. Together, these fixed surfaces ensure that the aircraft remains controllable and stable, especially during maneuvers and at different flight attitudes.

The other options, while related to flight control and stability, do not constitute the fixed surfaces of the empennage. Specifically, the elevators and rudder are movable control surfaces attached to the stabilizers but are not fixed themselves; the landing gear and flaps are components related to takeoff, landing, and ground handling, and trim tabs are small adjustable surfaces used to fine-tune control surface positions but are not considered part of the fixed structure of the empennage. Therefore, the vertical and horizontal stabilizers are the key components of the empennage's fixed surfaces.