What is the function of winglets at the end of each wing?

Winglets at the end of each wing serve a crucial role in enhancing fuel efficiency. They are designed to reduce aerodynamic drag by minimizing the formation of vortices that occur at the tips of the wings. These vortices create turbulence and lower lift, which can lead to an increase in fuel consumption as the aircraft requires more power to maintain speed and altitude. By improving the aerodynamics of the wing, winglets help the aircraft fly more efficiently, allowing it to use less fuel over the course of a flight. This not only contributes to cost savings for the airline but also reduces environmental impact through lower emissions.

The other options, while related to aircraft dynamics, do not accurately reflect the specific and primary function of winglets. For example, while winglets might have secondary impacts on aspects like cargo capacity or passenger comfort due to overall efficient flight operations, their main purpose is to improve fuel efficiency.