**Core Concept**
Pheochromocytomas are rare, catecholamine-secreting tumors arising from the adrenal medulla or sympathetic paraganglia. The excess catecholamines lead to various clinical manifestations, including hypertension, tachycardia, and sweating.

**Why the Correct Answer is Right**
Pheochromocytomas are characterized by the excessive secretion of catecholamines, such as epinephrine and norepinephrine. The clinical manifestations of pheochromocytoma are due to the effects of these catecholamines on the body. Options A, B, and D are all associated with pheochromocytoma due to the effects of catecholamines.

**Why Each Wrong Option is Incorrect**
**Option A:** Paroxysmal hypertension is a classic symptom of pheochromocytoma, occurring due to the sudden release of catecholamines.
**Option B:** Headache is a common symptom of pheochromocytoma, often due to the sudden increase in blood pressure.
**Option C:** Paroxysmal hypertension, headache, and sweating are all classic symptoms of pheochromocytoma. Therefore, this option should not be the correct answer.

**Clinical Pearl / High-Yield Fact**
The "Rule of 10s" for pheochromocytoma includes the following: 10% are bilateral, 10% are malignant, and 10% occur in children.

**Correct Answer: C.**