For the cell reaction
`Cu^(2+)(C_(1),aq.)+Zn(s)hArrZn^(2+)(C_(2),aq)+Cu(s)`
of an electrochemical cell, the change in free energy `(DeltaG)` of a given temperature is a function of
A. `lnC_(1)`
B. `lnC_(2)//C_(1)`
C. `ln (C_(1) + C_(2))`
D. `ln C_(2)`