Which one of the following is the correct percentage of the two ( out of the total of 4 ) green house gases that contribute to the total global warming ?

Question

$\begin {array} {1 1} (1)\;Methane\: 20\%,\: N_2O\: 18\% & \quad (2)\;CFCs\: 14\%,\: Methane\: 20\% \\ (3)\;CO_2\: 40\%,CFCs\: 30\% & \quad (4)\;N_2O\: 6\%, CO_2\: 86\% \end {array}$