Relative contributions of CO2, CH4, CFCs and N2O towards global warming are:
I. 50 %, 30 %, 10 % , and 10 % respectively
II. 60%, 20%, 14%, and 6% respectively
III. 40 %, 30%, 20% and 10% respectively
IV. None of the above
(a) Only II (b) Only III (c) Only I (d) None of the above