**Core Concept**
The question tests the student's knowledge of managing hyperkalemia, a condition characterized by elevated potassium levels in the blood, which can be life-threatening if not treated promptly. Hyperkalemia occurs when there is an imbalance between potassium intake, excretion, and cellular uptake.

**Why the Correct Answer is Right**
The correct answer, IV glucose and insulin, works by driving potassium into cells through the Na+/K+ ATPase pump. Insulin stimulates the pump, while glucose increases the cellular uptake of potassium. This mechanism is crucial in quickly lowering serum potassium levels in emergency situations. The combination of glucose and insulin can reduce serum potassium levels by 0.5-1.5 mEq/L within 15-30 minutes.

**Why Each Wrong Option is Incorrect**
**Option A:** IV calcium gluconate can help stabilize cardiac membranes and counteract the effects of hyperkalemia on the heart, but it does not lower serum potassium levels. Calcium gluconate is used as an adjunct therapy to manage cardiac complications of hyperkalemia.
**Option C:** Oral kayexalate in sorbitol is a potassium-binding resin that works by exchanging sodium or calcium for potassium in the intestine, which is then excreted in the stool. However, this mechanism is slower and less effective in emergency situations, taking several hours to lower serum potassium levels.
**Option D:** IV NaHCO3 can help shift potassium into cells by increasing the pH of the blood, but this effect is also slower and less reliable than the combination of glucose and insulin.

**Clinical Pearl / High-Yield Fact**
In emergency situations, the combination of glucose and insulin can quickly lower serum potassium levels, but it is essential to note that this effect is temporary and may not be sufficient to prevent cardiac complications. Long-term management of hyperkalemia often involves dietary changes, potassium-binding resins, and renal replacement therapy, such as dialysis.

**✓ Correct Answer: B. IV Glucose and insulin**