Which of the following are considered
natural carbon reservoirs?

select all that apply.

a. terrestrial biomass
b. fossil fuels
c. atmosphere
d. plastics

The answers are A, B, and C.

Explanation:

The question refers to the carbon cycle, interconnects four major reservoirs of carbon. This are the atmosphere, the terrestrial biosphere (including freshwater systems as well as non-living organic material,) the oceans (including living and non-living marine biota) and the sediments (including fossil fuels.) These exchanges between reservoirs happen because of different processes related to chemistry, physics, geology, and biology. So, the natural reservoirs are terrestrial biomass, fossil fuels, and atmosphere.