Which of the following is true? A. By the time you reach your 20's, your bones will reach their maximum strength. B. It is important that children get enough calcium and vitamin D to prevent osteoporosis. C. Most kids oroduce enough vitamin d. D. All of the above

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)

Ithink the answer is b hope this