Final answer:
The goal that involves constantly challenging training demands is progression, achieved by increasing intensity or frequency or by changing the target of the workouts.
Step-by-step explanation:
The goal that is aimed at constantly challenging training demands is progression. Progression in fitness means systematically increasing the demands on the body to improve fitness and performance. This can be done by methods such as increasing the intensity of workouts, increasing the frequency of training sessions, or altering the target muscle groups or skill sets. These changes force the body to adapt and improve.
The correct answer is c) Progression. In the context of physical training demands, progression refers to constantly challenging oneself by increasing the intensity, increasing the frequency, or altering the target of the training. This helps to avoid plateaus and continue making progress towards fitness goals.