Okay, let's tackle this question about the Na+/K+ pump. First, I need to remember what the Na+/K+ pump does. It's an active transport mechanism, right? It moves sodium out of the cell and potassium into the cell against their concentration gradients. The core concept here is the function of the Na+/K+ ATPase enzyme. This pump uses ATP to transport 3 Na+ ions out and 2 K+ ions in, maintaining the electrochemical gradient essential for nerve and muscle function.

Now, the correct answer should highlight this 3:2 ratio. Let's see the options. If the correct answer states that the pump moves 3 Na+ out and 2 K+ in, that's right. The other options might mix up the numbers or mention something else like using passive transport or different ion ratios. For instance, if an option says it uses passive transport, that's wrong because the pump is active. Another might say it moves equal numbers, which is incorrect. Also, some might confuse the direction of the ions.

Clinical pearl: The Na+/K+ pump is crucial for action potentials and maintaining resting membrane potential. It's a common target for drugs like digitalis, which inhibit the pump and are used in heart failure. So remembering the 3:2 ratio and active transport is key here. The correct answer should mention moving 3 Na+ out and 2 K+ in using ATP.

**Core Concept**
The Na⁺-K⁺ pump (Na⁺/K⁺-ATPase) is an active transport mechanism that maintains electrochemical gradients essential for neuronal and cardiac function. It hydrolyzes ATP to move 3 Na⁺ ions out of the cell and 2 K⁺ ions into the cell, consuming ~1/5 of cellular ATP.

**Why the Correct Answer is Right**
The pump operates via **conformational changes** in the ATPase enzyme. ATP phosphorylation causes a conformational shift, expelling Na⁺ and importing K⁺ against their gradients. This 3:2 stoichiometry is critical for **resting membrane potential**, **action potential propagation**, and **secondary active transport** (e.g., glucose reabsorption in kidneys). Its inhibition by cardiac glycosides (e.g., digoxin) increases intracellular Na⁺ and Ca²⁺, enhancing myocardial contractility.

**Why Each Wrong Option is Incorrect**
**Option A:** "Moves 2 Na⁺ out and 3 K⁺ in" – Incorrect stoichiometry; reverses the actual 3:2 ratio.
**Option B:** "Uses passive diffusion" – Passive transport does not require ATP or establish gradients.
**Option C:** "Located only in glomerular cells" – The pump is ubiquitous in eukaryotic cells, not restricted to kidneys.

**Clinical Pearl / High-Yield Fact**
The Na⁺/K⁺ pump is a **classic target for toxins** (e.g., ouabain) and **cardiac glycosides**. Remember the "3 out, 2 in" rule to avoid confusion with other transporters like the Na⁺/Ca²⁺ exchanger. This pump’s activity underpins **neurological signaling** and **cardiac function** – a high-yield topic for NEET and USMLE.

**Correct Answer: C. Moves 3 Na⁺ out and

✓ Correct Answer: A. Involves ATPase activity