Carbon dioxide is normally not a pollutant and is required to carry out normal photosynthesis by green plants. However, an excess concentration of carbon dioxide in the atmosphere due to the combustion of fossil fuels and industrialization leads to global warming. Biologically carbon dioxide is produced by the process of respiration in all living cells be they belong to plant or animals.
Animal cells, however, cannot carry out photosynthesis. If there is a decline in the number of plants and an increase in the number of animals; the balance between the production of carbon dioxide and the consumption of carbon dioxide will tilt in favor of the production of carbon dioxide.
So, the correct answer is 'Percentage of CO2