Which of the following is a true statement regarding mineral nutrients in soils and their implication for primary productivity? A) Globally, phosphorous availability is most limiting to primary productivity. B) Adding a nonlimiting nutrient will stimulate primary productivity. C) Adding more of a limiting nutrient will increase primary productivity, indefinitely. D) Phosphorous is sometimes unavailable to producers due to leaching. E) Alkaline soils are more productive than acidic soils.