Answer:
The answer is A: Plants fix carbon dioxide and release oxygen whereas animals take in oxygen and release carbon dioxide.
Step-by-step explanation:
Materials present on the earth surface cycle between the living systems and the environment. Carbon cycle is one such important cycle in which we see that carbon in the form of different compounds is cycled between living organisms and environment. The main process is photosynthesis and respiration. During photosynthesis, carbon is fixed in the form of CO2 from the atmosphere by the producers i.e. plants. In the process plants release O2 into the environment. Carbon enters back into the atmosphere due to respiration by the animals and combustion.