**Core Concept**
The equilibrium potential of a particular ion is the membrane potential at which there is no net movement of that ion across the cell membrane, according to the Nernst equation. In this case, we're looking at the equilibrium potential of chloride (Cl-) ions. The Nernst equation takes into account the concentration gradient of the ion across the membrane and the ion's charge.

**Why the Correct Answer is Right**
The equilibrium potential of Cl- ions (ECl) can be calculated using the Nernst equation: ECl = (RT/F) * ln([Cl-]out / [Cl-]in), where R is the gas constant, T is the temperature in Kelvin, F is Faraday's constant, and [Cl-]out and [Cl-]in are the concentrations of Cl- outside and inside the cell, respectively. This equation shows that the equilibrium potential of Cl- is dependent on the concentration gradient of Cl- across the membrane.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided, so we'll move on to the other distractors.
**Option B:** This option is incorrect because it doesn't provide a valid calculation for the equilibrium potential of Cl- ions.
**Option C:** This option is incorrect because it doesn't take into account the concentration gradient of Cl- across the membrane.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the equilibrium potential of an ion is not the same as its resting membrane potential. The resting membrane potential is influenced by the equilibrium potentials of multiple ions, including K+, Na+, and Cl-.

**Correct Answer:** ECl = (RT/F) * ln([Cl-]out / [Cl-]in)