What is the purpose of using a rudder on an aircraft?

The primary purpose of using a rudder on an aircraft is to maneuver the aircraft left and right, which involves controlling the yaw motion. The rudder is a vertical control surface located on the tail of the aircraft, and it works by redirecting airflow, allowing the pilot to adjust the aircraft's heading and maintain coordinated flight. When the rudder is deflected to one side, it creates a force that causes the nose of the aircraft to rotate in that direction, enabling smooth turns and maintaining stability, especially during crosswind conditions or when other forces are acting on the aircraft.

The other options, while related to aircraft control, do not correctly describe the function of the rudder. Elevation is managed by the elevator, roll control is primarily managed by the ailerons, and drag reduction involves various aerodynamic features and surfaces that are different from the rudder's primary purpose.