What is the primary purpose of flaps in a Cessna 172?

Flaps in a Cessna 172 are primarily used to increase lift during takeoff and landing phases of flight. When deployed, flaps change the shape of the wing, allowing it to generate more lift at lower speeds, which is crucial during these critical phases when the aircraft is operating close to stall speed. This additional lift enables the aircraft to take off and land in shorter distances, enhancing safety and performance.

In contrast to other options, the idea that flaps would increase engine efficiency, control cabin pressurization, or decrease drag at cruising altitude does not align with their intended design and function. Flaps are geared specifically toward improving aerodynamic performance during takeoff and landing rather than influencing engine operation or behaving as a drag-reducing mechanism at cruising altitudes.