In a Galvanic cell, a full redox reaction takes place, one half-reaction at each electrode. How is the cell potential calculated?

a) it can only be estimated from the reactivity series
b) it is experimentally determined
c) By multiplying the cathode potential and the anode potential
d) by subtracting the anode potential from the cathode potential

d) by subtracting the anode potential from the cathode potential