Which part of the aircraft is essential for controlling the left and right movement?

The aileron is the correct part of the aircraft responsible for controlling the left and right movement, specifically during roll maneuvers. Ailerons are located on the trailing edges of the wings and work by altering the lift on each wing; when an aileron on one wing is deflected upward, it reduces lift on that side, causing the aircraft to roll toward the wing with the aileron deflected downward, which increases lift on that side. This rolling motion is crucial for executing turns and maintaining control during flight.

The rudder primarily influences the yaw movement of the aircraft, which is the left and right movement of the nose around the vertical axis. While it plays a significant role in coordinating turns, it does not directly control the aircraft's rolling motion like ailerons do. The elevator is responsible for controlling the pitch movement, enabling the aircraft to climb or descend. Winglets, found at the ends of the wings, are designed to improve aerodynamic efficiency and reduce drag but do not have a role in controlling movement directly.