Correct Answer: absorption of carbon dioxide

Solution : The correct answer is absorption of carbon dioxide.

Forests are vital for maintaining ecological balance, livelihood of various animals and sustenance of life, but the main function of forests is carbon sequestration. Forests absorb the carbon dioxide and release oxygen because of which they act as a big carbon sink. Plants perform photosynthesis in which they take up carbon dioxide and sunlight and covert it into glucose. In this process they take up excess carbon dioxide from atmosphere and keep it under ambient levels for sustenance of life.