Consider the following half-reactions with their standard reduction potentials. 

(a) Au⁺(aq) + e^– → Au(s)              E°_red = 1.692 V
(b) Cr²⁺(aq) + 2 e^– → Cr(s)           E°_red = –0.913 V
(c) Zn²⁺(aq) + 2 e^– → Zn(s)          E°_red = –0.763 V
(d) Bi³⁺(aq) + 3 e^– → Bi(s)            E°_red = 0.308 V

Identify the combination of these half-cell reactions that will results in an overall reaction with the smallest positive E°_cell, then provide the value of E°_cell.