Which aspect of fitness is defined as the ability to exercise for a long period of time?

The correct answer is defined as stamina, which refers specifically to the body's ability to sustain prolonged physical activity. Stamina is crucial in dance, as it allows a dancer to execute movements and routines over an extended period without becoming excessively fatigued. This endurance is vital not only for performance but also for practice sessions, as dancers often need to be on their feet and moving for long durations.

Core strength, while important for balance and control, focuses on the stability and power of the central muscles of the body rather than the ability to maintain exercise over time. Speed pertains to how quickly movements can be executed, which is not the same as the ability to perform across an extended timeframe. Agility is related to quick and graceful changes in position and direction, highlighting coordination and reflexes instead of sustaining activity. In summary, stamina is the appropriate term for the capability to engage in extended physical exertion effectively.