Which of the following best defines agility?

Agility is best defined as the ability to change direction quickly and efficiently. This skill is crucial in various sports and physical activities where quick movements and rapid changes in positioning are necessary. Agility involves a combination of speed, coordination, balance, and reaction time, enabling an individual to respond effectively to dynamic challenges, such as opponents or obstacles in their path.

In contrast, the other choices focus on different aspects of physical fitness or performance. Maintaining balance is a component of stability, which is important for overall coordination but does not encompass the rapid directional changes that define agility. Running long distances pertains to endurance, which is a measure of how well the body can sustain prolonged physical activity but does not relate to the quick, sharp movements associated with agility. Similarly, lifting heavy weights relates to strength rather than agility, emphasizing one's capacity to exert force rather than the ability to move efficiently in various directions.