What is the primary flight control used for roll?

The primary flight control used for roll is the ailerons. Ailerons are hinged surfaces located on the outer sections of the wings, and they work in opposition to one another to control the aircraft's roll about its longitudinal axis. When the pilot moves the control yoke or stick to the left, the left aileron moves up while the right aileron moves down. This causes the left wing to decrease in lift and the right wing to increase in lift, resulting in a roll to the left.

In contrast, elevators control pitch, which refers to the aircraft's angle of climb or descent. The rudder controls yaw, affecting the aircraft's direction left or right relative to its nose. Flaps are used primarily to increase lift during low-speed operations, such as takeoff and landing, but they do not contribute to roll control. Thus, the ailerons are specifically designed for rolling maneuvers, making them the correct answer to the question.