**Core Concept**
Primary hyperaldosteronism is a condition characterized by excessive production of aldosterone, a hormone produced by the adrenal glands that regulates sodium and potassium balance in the body. This leads to hypertension, hypokalemia, and metabolic alkalosis.

**Why the Correct Answer is Right**
Aldosterone excess in primary hyperaldosteronism is usually due to an aldosterone-producing adenoma (APA), bilateral adrenal hyperplasia, or familial hyperaldosteronism. The excess aldosterone promotes the retention of sodium and water, leading to hypertension and hypokalemia. The kidneys respond to the increased potassium load by secreting more potassium in the urine, resulting in hypokalemia.

**Why Each Wrong Option is Incorrect**
**Option A:** Hypokalemia is a characteristic feature of primary hyperaldosteronism. It occurs due to increased potassium excretion in the urine. This option is incorrect because hypokalemia is not a feature of primary hyperaldosteronism; it is a key characteristic.

**Option B:** Metabolic alkalosis is a feature of primary hyperaldosteronism. It occurs due to the increased excretion of hydrogen ions in the urine, which is a result of increased aldosterone activity. This option is incorrect because metabolic acidosis is not a feature of primary hyperaldosteronism; metabolic alkalosis is the correct association.

**Option C:** Hypertension is a feature of primary hyperaldosteronism. It occurs due to the increased retention of sodium and water, which increases blood volume and blood pressure. This option is incorrect because hypertension is a feature of primary hyperaldosteronism; it is not an exception.

**Clinical Pearl / High-Yield Fact**
Aldosterone-producing adenomas can be identified using imaging studies like CT or MRI, and they are often unilateral. In contrast, bilateral adrenal hyperplasia is usually associated with familial hyperaldosteronism.

**Correct Answer: A. Hypokalemia**