The correct answer is option B
Carbon dioxide is present in the environment along with the other gases and still it is considered as a pollutant when its concentration in the atmosphere increases than the normal concentrations.
The normal concentration of the carbon dioxide is maintained by the help of plants that use carbon dioxide for the process of photosynthesis.
The increased amount of carbon dioxide in the atmosphere is caused due to the human activity.
Industrial release, pollution from automobiles are some of the sources of carbon dioxide emission.
