## Core Concept
Pheochromocytomas are rare tumors of the adrenal glands that produce excess catecholamines, such as epinephrine and norepinephrine. The clinical presentation of pheochromocytoma is variable but often includes symptoms related to excessive catecholamine release, such as hypertension, tachycardia, sweating, and palpitations.

## Why the Correct Answer is Right
The correct answer, , is associated with hypokalemia which is not a typical feature of pheochromocytoma. Pheochromocytomas primarily cause hypertension due to the effects of catecholamines on alpha-adrenergic receptors, leading to vasoconstriction. However, they can also cause tachycardia and palpitations through beta-1 adrenergic receptor stimulation. Metabolic effects may include hyperglycemia and lactic acidosis. However, hypokalemia is not a direct or typical consequence of the catecholamine excess seen in pheochromocytoma; in fact, some patients might exhibit mild hyperkalemia due to the effects of aldosterone suppression.

## Why Each Wrong Option is Incorrect
* **Option A:** Hypertension is a classic feature of pheochromocytoma due to the excessive release of catecholamines, which stimulate alpha-adrenergic receptors, causing vasoconstriction.
* **Option B:** Tachycardia can occur due to the stimulation of beta-1 adrenergic receptors in the heart by catecholamines.
* **Option C:** Diaphoresis (sweating) is a common symptom, likely due to the adrenergic effects of catecholamines on the sympathetic nervous system.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that pheochromocytoma can present with the classic triad of episodic headaches, sweating, and tachycardia, but not all patients exhibit all three symptoms. Additionally, while hypertension is a hallmark, it can be paroxysmal or sustained.

## Correct Answer: D.