P-V plots for two gases during adiabatic process are shown in the figure. Plots 1 and 2 should correspond respectively to [IIT-JEE (Screening) 2001]

• A.            He and \[{{O}_{2}}\]
• B.            \[{{O}_{2}}\] and He
• C.            He and Ar
• D.            \[{{O}_{2}}\] and \[{{N}_{2}}\]