Answer: A. Plants use CO2 but do not release any, thus maintaining a balance of CO2 in the atomsphere.
Plants are autotrophs and this means they are capable of manufacturing their own food. This process is known as photosynthesis. In photosynthesis, CO2 is utilized by plants together with water in the presence of sunlight to produce glucose and oxygen gas. With this, plants tend to create in balance the amount of Carbon dioxide in the body. Animals on the other hand inhale oxygen from their environment and release carbon dioxide in return. This entire respiratory process of plants and animals helps in creating a balance between the CO2 and O2 levels in the atmosphere. Plants take in CO2 and will not release any thus maintaining a balance in the amount of CO2 in the environment.