What enables an individual to perform activities without undue fatigue?

Muscular endurance is the correct answer because it refers to the ability of a muscle or group of muscles to repeatedly exert force over an extended period of time without experiencing fatigue. This capability is vital for various daily activities, allowing individuals to perform tasks such as lifting, carrying, or engaging in recreational sports without becoming overly tired. Enhanced muscular endurance supports sustained physical activities, making it essential for maintaining performance in both athletic and non-athletic pursuits.

On the other hand, body composition involves the proportion of fat and non-fat mass in the body, which affects overall health and physical appearance, but does not directly determine the ability to perform continuous activities. Cardiovascular fitness relates to the efficiency of the heart and lungs in supplying oxygen during sustained physical activity; while important, it specifically focuses on aerobic capacity rather than the ability of muscles to sustain activity. Flexibility, which refers to the range of motion in joints and muscles, supports performance in various activities but does not directly measure endurance or fatigue levels. Thus, muscular endurance is uniquely characterized by its role in enabling individuals to engage in prolonged physical activities effectively.