Use the information you learned about carbon-based molecules to explain a human's need to participate in the biogeochemical cycles.

Human releases carbon dioxide during respiration and also certain activities performed by him  lead to generation of carbon which at some stage become the part of biogeochemical cycle.

Explanation:

Carbon is an elementary part of all living beings and thus is found in almost all the living organism and human as an evolved species has the ability to take in oxygen and release carbon dioxide.  

This released carbon dioxide enters into the biogeochemical cycles (predominantly the carbon cycle) and get converted into useful form again after going through a cyclical process via various biotic and abiotic stages.  

Also certain human activities like burning of fossil fuels, wood etc also releases carbon based product such as carbon di-oxide, carbon mono-oxide etc, . These products from unnatural process also become part of biogeochemical cycle.  

answer: the answer is b