a' and 'b' are van der Waals' constants for gases. Chlorine is more easily liquefied than ethane because

Question

( A ) a and b for $Cl_2$ < a and b for $C_2H_6$
( B ) a for $Cl_2$ > a for $C_2H_6$ but b for $Cl_2$ < b for $C_2H_6$
( C ) a and b for $Cl_2$ > a and b for $C_2H_6$
( D ) a for $Cl_2$ < a for $C_2H_6$ but b for $Cl_2$ > b for $C_2H_6$