A 20.00-mL aliquot of 0.100 M Fe²⁺ solution is titrated with 0.100 M Ce⁴⁺. (a) Calculate the potential of the indicator cathode with respect to SHE after addition of 10, 18.00, 19.80, 19.98, and 20.00 mL.

a) 0.57 V
b) 0.62 V
c) 0.68 V
d) 0.75 V