**Core Concept**
Hypercalcemia is a clinical condition characterized by elevated serum calcium levels, which can result from various etiologies including hormonal imbalances, vitamin D toxicity, and chronic kidney disease. The pathophysiology of hypercalcemia involves the increased absorption of calcium from the gastrointestinal tract, bone resorption, or impaired renal excretion.

**Why the Correct Answer is Right**
Furosemide, a loop diuretic, actually corrects hypercalcemia by increasing urinary calcium excretion. This is in contrast to other options which directly contribute to hypercalcemia. **Option B**, Vitamin D intoxication, leads to increased absorption of calcium from the gut. **Option C**, Sarcoidosis, is a granulomatous disease that stimulates the production of 1,25-dihydroxyvitamin D, resulting in hypercalcemia. **Option A**, Thyrotoxicosis, can cause hypercalcemia due to increased osteoclastic activity and bone resorption.

**Why Each Wrong Option is Incorrect**
**Option A:** Thyrotoxicosis is known to cause hypercalcemia through increased osteoclastic activity and bone resorption, making it a correct cause of hypercalcemia.
**Option B:** Vitamin D intoxication directly contributes to hypercalcemia by increasing calcium absorption from the gut.
**Option C:** Sarcoidosis stimulates the production of 1,25-dihydroxyvitamin D, leading to increased calcium absorption and hypercalcemia.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that loop diuretics like Furosemide can actually correct hypercalcemia by increasing urinary calcium excretion, whereas thiazide diuretics can worsen hypercalcemia by decreasing urinary calcium excretion.

**Correct Answer Line**
✓ Correct Answer: D. Furosemide