Answer:
D. They show how certain compounds and elements move through the environment and are continually used and recycled
Explanation:
The biogeochemical cycles are the cycles through which the chemical compounds are moving through the different spheres, both abiotic and biotic, and they get constantly used and constantly recycled through them. This basically means that the biogeochemical cycles are the ones that occupy every sphere, as they are what units all of the spheres. By moving through all of the spheres, the chemicals change their composition, getting used, dissolved, merged with other chemicals, and at the end they get recycled and the process continues all over again.
