Which two forces contribute to an increase in the angle of attack (AOA) of an airfoil?

To understand why the correct choice indicates that lift and drag contribute to an increase in the angle of attack (AOA) of an airfoil, it is essential to explore the dynamics of how an airfoil interacts with airflow.

The angle of attack refers to the angle between the chord line of the airfoil and the incoming airflow. When the AOA increases, there are changes in both lift and drag forces acting on the airfoil. As the AOA increases, the airflow over the wing accelerates and the pressure distribution changes, which contributes to an increase in lift due to the Bernoulli principle. The increased lift is desirable, particularly in conditions where a pilot or automated system is trying to gain altitude or enhance performance.

At the same time, as the AOA increases, the drag also increases. The drag force is associated not only with the friction between the air and the airfoil surface but also with the increased lift-to-drag ratio initially up to a certain point. Therefore, as you increase the AOA, you will experience a rise in both lift (up until the stall point) and drag, making the combination of these two forces integral to the manipulation of AOA.

In contrast, the other choices do not effectively address the combination