You should try to plan your fitness goal around the of Fitness and the Principle.

Ithink it's choice d (antibiotic resistance)

People who utilizes the progression principle will ensure their exercise program increases in frequency, intensity, time, and type. the changes need to happen gradually in order to ensure they make gains in their fitness program. a person who doesn't utilize the progression principle can still gain health benefits from exercising, but will not continue to improve in cardiovascular fitness.

1. the answer is a parasite