If the left rudder is pressed, what will happen to the aircraft?

Pressing the left rudder will cause the aircraft to turn or yaw to the left. The rudder is a control surface located on the vertical stabilizer (tail fin) of the aircraft, and it is designed to control the aircraft's yaw motion—this is the movement around the vertical axis. When the left rudder is applied, it deflects to the left, which increases the lateral force on the tail of the aircraft. This causes the nose of the aircraft to move left, resulting in a leftward turn. Yawing to the left is a response directly influenced by the rudder's action.

Understanding how the rudder affects the plane's yaw is essential for pilots, as it plays a crucial role in maintaining coordinated flight, especially during turns. The other options pertain to different types of movement or responses that are not directly influenced by rudder input. For example, ascending involves vertical control surfaces and lift, rolling is related to ailerons and lateral stability, and stalling refers to a loss of lift due to excessive angle of attack rather than rudder control.