The correct answer is: A. Carbon dioxide
Deforestation is the permanent removal of trees to make room for something besides forest. This can include clearing the land for agriculture or grazing, or using the timber for fuel, construction or manufacturing.
When trees are cut down, they release the carbon dioxide they have stored in their tissues into the atmosphere. This contributes to climate change, as carbon dioxide is a greenhouse gas that traps heat in the atmosphere.
Nitrogen is an essential element for plant growth, and it is also a major component of the atmosphere. Deforestation does not have a significant impact on the amount of nitrogen in the atmosphere.
Oxygen is another essential element for plant growth, and it is also a major component of the atmosphere. Deforestation does not have a significant impact on the amount of oxygen in the atmosphere.
Sulphur dioxide is a pollutant that is released into the atmosphere from a variety of sources, including power plants, factories and vehicles. Deforestation does not have a significant impact on the amount of sulphur dioxide in the atmosphere.
In conclusion, the gas that is likely to be reduced in the atmosphere by deforestation is carbon dioxide.