Final answer:
the correct option is d. Adjustability and balance play both positive and negative roles in exercise machines. Adjustability enhances workout efficiency, while balance ensures a stable workout.
Step-by-step explanation:
Adjustability and balance play both positive and negative roles in exercise machines. Adjustability allows for customization, which enhances workout efficiency by allowing users to tailor the machine to their specific needs and goals.
For example, adjustable resistance on a stationary bike can make the workout more challenging as the user gets stronger. On the other hand, balance ensures a stable workout and helps prevent muscle strain and injuries. A well-balanced exercise machine will have a sturdy base and ergonomic design to support the user's movements and maintain proper alignment.