Which statement is true about the factors affecting physical fitness? a. we have no control over any of the factors. b. we have total control over all the factors. c. the factors that affect physical fitness only apply to athletes. d. we can control some of the factors, but not all of them.

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)

The answer is sensory neruon