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.