If a Plant Is Primarily Limited by Nitrogen and Secondarily

Multiple Choice

If a plant is primarily limited by nitrogen and secondarily by phosphorus, according to Leibig's law of the minimum, under which circumstances would adding phosphorus increase the plant's growth rate?

A) if nitrogen and phosphorus are added together
B) if the phosphorus is added to alleviate limitation before the nitrogen is added
C) if the nitrogen is added to alleviate limitation before phosphorus is added
D) Phosphorus would never increase the growth rate because the primary limitation is nitrogen.