Correct Response: C. The phosphorus cycle is a biogeochemical cycle and differs from the other cycles in that phosphorus is a mineral that does not change into a gaseous state. In the phosphorus cycle, the phosphorus becomes part of a chemical compound (phosphate) and so does not stay in the same chemical form (A). Human activities contribute to the phosphorus cycle as well as to the carbon and nitrogen cycles. Both phosphorus and nitrogen can be released into the environment through use of fertilizers, and carbon is released into the atmosphere through the burning of fossil fuels (B). Organisms require phosphorus for growth and phosphorus can be a limiting factor (D) in some ecosystems when there is not enough present in the environment.
