**Core Concept**
Na+-K+ ATPase, also known as the sodium-potassium pump, is an enzyme complex responsible for maintaining the electrochemical gradient across the plasma membrane of cells by pumping sodium ions out and potassium ions into the cell against their concentration gradients, using ATP as an energy source.

**Why the Correct Answer is Right**
The correct answer is sodium-potassium pump because it accurately describes the primary function of Na+-K+ ATPase. This pump is essential for maintaining the resting membrane potential, regulating cell volume, and facilitating the transmission of nerve impulses. It works by binding to ATP, hydrolyzing it to ADP and Pi, and using the energy to transport three sodium ions out of the cell and two potassium ions into the cell through a conformational change in the pump's structure.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the primary function of Na+-K+ ATPase.
* **Option B:** This option is incorrect because it is a different type of pump that facilitates the transport of ions across the cell membrane, but it is not the sodium-potassium pump.
* **Option C:** This option is incorrect because it is a different type of pump that is involved in the transport of ions across the cell membrane, but it is not the sodium-potassium pump.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the sodium-potassium pump is an energy-dependent process that requires ATP to maintain the electrochemical gradient across the plasma membrane. This process is crucial for the proper functioning of the nervous system, and disruptions in this process can lead to various neurological disorders.

**Correct Answer: D. Sodium-potassium pump**