Which of the foll. is true about biogeochemical cycles? a. phosphorus cycle involves recycling of atmospheric phosphorus b. phosphorus cycle is a cycle that involves weathering of rocks c. carbon cycle is a localized cycle that primarily involves burning of fossil fuels d. carbon cycle has maintained a constant atmospheric concentration of CO2 for the past several million years. e. nitrogen cycle involves movement of diatomic N between the different abiotic components of the ecosystem.