The molar excess Gibbs free energy, gE, for a binary liquid mixture at T and P is given by, (gE/RT) = A . x1. x2, where A is a constant. The corresponding equation for ln y1, where y1 is the activity co-efficient of component 1, is

A. A . x22

B. Ax1

C. Ax2

D. Ax12

Please do not use chat terms. Example: avoid using "grt" instead of "great".