At which angle of attack is the drag minimized for an airplane?

The angle of attack at which the drag is minimized for an airplane typically occurs at a lower angle within the operational range of flight, often around the angle of attack that corresponds to the best lift-to-drag ratio. This concept is crucial for efficient flight performance as it helps pilots utilize lift effectively while reducing resistance caused by drag.

At lower angles of attack, the airflow remains predominantly attached to the wing, which allows for a more streamlined flow around the aircraft. As the angle increases beyond a certain point, drag will begin to increase due to the onset of flow separation and other aerodynamic factors. The optimal angle for minimal drag is usually found below the critical angle of attack, often in the range of 6 to 10 degrees, depending on the specific aircraft design.

In this question, selecting the option corresponding to 6 degrees accurately reflects the general understanding of aerodynamics, where lower angles of attack are associated with reduced drag, hence maximizing efficiency during flight.