## **Core Concept**
The resting membrane potential (RMP) is primarily generated by the differential distribution of ions (mainly sodium [Na+] and potassium [K+]) across the cell membrane and the selective permeability of the membrane to these ions. The Na+/K+ pump, also known as the sodium-potassium pump, plays a crucial role in maintaining the concentration gradients of sodium and potassium ions across the cell membrane.

## **Why the Correct Answer is Right**
The Na+/K+ pump contributes to the development of the RMP by actively transporting 3 sodium ions out of the cell and 2 potassium ions into the cell against their concentration gradients, using the energy from the hydrolysis of one ATP molecule. This action directly contributes to the negative charge inside the cell by removing positively charged sodium ions and adding positively charged potassium ions, although the effect on the membrane potential is more related to the sodium removal. The pump's activity helps to maintain the high concentration of potassium ions inside the cell and the high concentration of sodium ions outside the cell, which is essential for the generation and maintenance of the RMP.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not accurately reflect the contribution of the Na+/K+ pump to the RMP. Without specific values, it's hard to assess directly, but typically, the pump's direct contribution to the membrane potential is considered minimal compared to the diffusion of ions through leak channels.
- **Option B:** This option is incorrect because, similar to option A, it does not accurately quantify or qualify the role of the Na+/K+ pump in establishing the RMP. The actual membrane potential is largely determined by the permeability of the membrane to potassium ions (through potassium leak channels) and the concentration gradient of potassium ions.
- **Option C:** While this might seem like a plausible option, the correct understanding is that the Na+/K+ pump's primary role is not directly setting the RMP but maintaining the ion gradients. The RMP is largely established by the diffusion of potassium ions out of the cell through leak channels.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that while the Na+/K+ pump is crucial for maintaining the ion gradients that allow the RMP to be generated and maintained, the RMP itself is largely determined by the movement of potassium ions through potassium leak channels. The Na+/K+ pump's activity is essential for long-term maintenance of these gradients but does not directly set the RMP.

## **Correct Answer:** .