Essential life materials, like nitrogen and carbon, are exchanged and recycled through
biogeochemical cycles
earth's core
volcanic activity
convection and condensation

The answer is A, biogeochemical cycles.

Biogeochemical Cycles.  

Explanation:

In Earth Science and ecology, a biogeochemical cycle or cycling of substances refers to a pathway by which a chemical component mediates via biosphere (biotic) and lithosphere, atmosphere, and hydrosphere (abiotic) constituents of the Earth.  

There are biogeochemical cycles for the chemical elements carbon, mercury, calcium, hydrogen, phosphorus, nitrogen, sulfur, selenium, and oxygen. The important life constituents, like carbon and nitrogen, are recycled and exchanged via biogeochemical cycles.  

i'm assuming that the correct answer is indeed the first one/ "a"..

the answer is b & c i believe : )