What is the primary purpose of flaps?

Flaps are designed primarily to increase lift at lower speeds, which is critical during takeoff and landing phases of flight. When deployed, flaps change the wing's airfoil shape, increasing the wing's camber and surface area. This allows the wing to generate more lift without requiring an increase in speed. As a consequence, pilots can safely operate the aircraft at slower speeds, which is particularly beneficial during the crucial phases of ascent and descent.

This enhancement in lift at reduced velocities helps to reduce the required takeoff distance and allows for steeper approaches and shorter landing distances, thereby improving overall safety and efficiency during these critical flight phases.

The other options do not accurately reflect the primary function of flaps. While flaps can have secondary effects on drag and stability, their main purpose is directly related to improving lift for safer low-speed operations.