Which of the following is an example of a primary flight control?

Ailerons serve as critical components of a primary flight control system. They are primarily responsible for controlling the aircraft's roll about its longitudinal axis, allowing the pilot to bank the aircraft during turns. The correct operation of ailerons is essential for effective maneuvering and maintaining stability during flight.

While flaps and slats enhance lift and improve low-speed handling characteristics, they are classified as secondary flight controls since they supplement the primary controls rather than directly manipulating the aircraft's attitude or flight path in a fundamental way. Trim tabs also fall under secondary controls, as they assist in maintaining a desired flight attitude by relieving control pressures, but they do not actively change the aircraft's attitude like ailerons do. Thus, ailerons stand out as essential flight controls directly influencing the aircraft's performance during various maneuvers.