Concept: This question tests your understanding of the active transport mechanism of the Sodium-Potassium pump, a crucial process for maintaining cell membrane potential and cell volume.

Why (B) is correct: The Sodium-Potassium pump (Na+/K+ ATPase) is an active transport protein that uses energy from ATP hydrolysis to move ions against their concentration gradients. Specifically, it pumps 3 sodium ions (Na+) outwards from the cell and 2 potassium ions (K+) inwards into the cell. This creates an electrochemical gradient essential for nerve impulse transmission, muscle contraction, and maintaining osmotic balance.

Why other options are wrong:

• (A) Incorrect number and direction of ions.
• (C) Incorrect ions being pumped outwards and inwards, and incorrect numbers.
• (D) Incorrect ions being pumped outwards and inwards, and incorrect numbers.

Common Mistake: Students often confuse the number of Na+ and K+ ions transported or their direction of movement. Remember it's 3 Na+ out and 2 K+ in.

NEET Tip / Mnemonic: Think of it as "Na-K-3-2-OUT-IN". Na goes OUT (3 ions), K goes IN (2 ions).

Correct Answer: (B)