单项选择题

A.φ=φθ(Ox/Red)+RT/nF·lna(Ox)/a(Red)
B.φ=φθ(Ox/Red)-RT/nF·lna(Ox)/a(Red)
C.φ=φθ(Ox/Red)+RT/nF·lga(Ox)/a(Red)
D.φ=φθ(Ox/Red)-RT/nF·lga(Ox)/a(Red)