Living systems consist of organisms interacting with their environments. the carbon cycle is an example of a living system.

assuming the carbon cycle is a closed system, which of the following statements is true?

a. when all the fossil fuels are used up, there will be no more carbon.

b. as population sizes increase, more carbon is produced.

c. mass and energy are conserved in the carbon cycle.

d. the sun absorbs energy from the carbon cycle.