Answer
Choice B.
Work Step by Step
We are told that the platinum electrode behaves like an ideal capacitor, in series with the extracellular fluid’s resistance.
For a DC signal, $\omega=0$. The impedance of the capacitor $X_C=\frac{1}{\omega C}$ goes to infinity at zero frequency. This is in series with the fluid’s resistance, so the overall dc impedance is also infinite.
