Which of the following nutrients provides structure to cells, tissue, and muscle?

a. carbohydrates
b. proteins
c. fats
d. minerals

Answer is B.

The main components of the cellular cytoskeleton include microfilaments, microtubules and intermediate filaments which are composed of the proteins actin, tubulin, and [many different proteins] respectively.

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)