Is used by the body to synthesize vitamin d, maintain the proper functioning of nerve cells, to keep skin soft and supple, and to transport fat to cells.
carbohydrate
protein
cholesterol

Proetien. Protein. Protein. Portein. Protein is the correct answer. This is not a very hard question. You could probally find it online if you really tried. 

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.