Which is a true statement regarding the law of mass balance? A.Solids, gases, and liquids have their own specific equations for the law of mass balance. B.When the body converts a nutrient to another substance, there is no effect on mass balance. C.The law of mass balance applies to the input/output relationship of solids, liquids, and gases. D.The law of mass balance states that substances in the body are kept at constant levels because the human body is a closed system.