Regarding the assertion and reason, choose the correct option.
Assertion [A]: Deforestation is one main factor contributing to global warming.
Reason [R]: Besides, CO2, methane and CFCs are also greenhouse gases.
Carbon dioxide is an important greenhouse gas and it is necessary that it is present in the correct amounts in the atmosphere so that the normal temperature of the earth is maintained. Trees are mostly responsible for maintaining balanced carbon dioxide levels on earth. However, due to increased deforestation, the carbon dioxide levels have been continually rising as there are not enough trees to ultilise the excess carbon dioxide emitted from our automobiles, industries etc. While carbon dioxide is the major contributor to global warming, methane and CFCs are other greenhouse gases which also contribute to it.