D. Calcium cycle
Biogeochemical cycles are not an important part of the Earth system.
Calcium cycle is not a regular model found in the Earth system. Rock cycles represent the time consuming changes through geologic time among three principle types: sedimentary, metamorphic, and igneous. Hope this helps! Have a blessed day! And also good luck!
i think it would be b. tissue because an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.
a rock cycle