What happens when humans burn fossil fuels?

a)carbon is released into the atmosphere.

b)carbon is removed from the atmosphere.

c)temperatures on earth decrease.

d)carbon is destroyed.

When we burn fossil fuel it gives energy in the form of heat and or light

the fossil fuels are made up of carbon hydrogen and other elements

on burning fossil fuels undergo combustion

during combustion the carbon present in the fossil fuel reacts with oxygen to form carbon dioxide

this carbon dioxide is emitted as gas and thus gets released in environment,

C  + O2(g)  ---> CO2(g)

Thus answer is

A)Carbon is released into the atmosphere.