A: Standing state refers to the amount of nutrients such as carbon, nitrogen, phosphorous, calcium etc, present in the soil at any given time. It varies in different kinds of ecosystems and also on a seasonal basis.
B : Gaseous cycle include those of nitrogen, oxygen, carbon, and water. In this cycle, the reservoir is the air or the oceans (via evaporation).
C : Standing crop is the total biomass of an ecosystem or any of its components at a given time. The standing crop is measured as the mass of living organisms or the number in a unit area.
D : Sedimentary cycles include those of iron, calcium, phosphorus, and other more earthbound elements. In this cycle, the reservoir is the Earth's crust.