**Core Concept**
Pheochromocytoma is a rare, usually benign, tumor of the adrenal gland that secretes excessive amounts of catecholamines, leading to hypertension, tachycardia, and other systemic symptoms. The primary goal of treatment is to control the excessive catecholamine production.

**Why the Correct Answer is Right**
The treatment of choice for pheochromocytoma involves surgical resection of the tumor. **Preoperative alpha-blockade** is crucial to prevent hypertensive crises during surgery. This is achieved through the use of medications like **phenoxybenzamine**, which blocks alpha-adrenergic receptors, thereby reducing the vasoconstrictive effects of catecholamines. The correct answer is a medication that is used for preoperative alpha-blockade in pheochromocytoma.

**Why Each Wrong Option is Incorrect**
**Option A:** Metoprolol is a beta-blocker, which is contraindicated in pheochromocytoma until alpha-blockade is established, as it can precipitate a hypertensive crisis by unopposed alpha-receptor stimulation.
**Option B:** Spironolactone is a potassium-sparing diuretic and has no role in the management of pheochromocytoma.
**Option C:** Furosemide is a loop diuretic that can be used to manage hypertension in the context of pheochromocytoma, but it is not the primary treatment for preoperative alpha-blockade.

**Clinical Pearl / High-Yield Fact**
Remember that **phenoxybenzamine** is the alpha-blocker of choice for preoperative management of pheochromocytoma, as it has a long duration of action and can be titrated to achieve optimal blockade.

**Correct Answer:** C. Phenoxybenzamine