Answer: Atmosphere and hydrosphere.
Step-by-step explanation:
Carbon is a very important element found on earth. It is found in lithosphere, hydrosphere, atmosphere, et cetera.
The most abundant form of carbon can be found in atmosphere in the form of carbon dioxide. This is released by the burning of fossil fuels, smoke released from automobiles, et cetera.
Hydrosphere also contains a huge amount of carbon in it. The dissolve carbon in water is in the form of carbonic acid and as the oceans covers a wide range of earth's surface so the amount of carbon present in there is also more.