How does a plane benefit from a retractable landing gear?

A retractable landing gear provides significant aerodynamic advantages for an aircraft, primarily by reducing drag during flight. When the landing gear is extended, it creates additional drag due to the disruption of airflow around the aircraft’s fuselage. By retracting the landing gear into the aircraft's body, the overall aerodynamic shape is streamlined, leading to a more efficient airflow and a reduction in drag.

This aerodynamic efficiency translates to enhanced fuel efficiency, as the engines can work less hard to maintain the same speed and altitude with lower drag than would be experienced with landing gear extended. This is especially important for faster aircraft that operate at higher speeds where drag plays a more significant role in overall performance.

In contrast to the benefits provided by retractable landing gear, aspects such as weight capacity, stability during flight, and control during landing are influenced by other design features and operational practices rather than the retractability of the landing gear itself. Therefore, the correct answer highlights the primary advantage of retractable landing gear in terms of fuel efficiency and drag reduction.