**Core Concept**
Hypertension with hypokalemia is often related to **primary aldosteronism**, a condition characterized by the excessive production of **aldosterone**, a hormone that regulates electrolyte balance and blood pressure. This condition leads to increased sodium reabsorption and potassium excretion in the kidneys.

**Why the Correct Answer is Right**
The correct answer is related to the effect of **aldosterone** on the kidneys, promoting sodium retention and potassium excretion, leading to **hypokalemia** and **hypertension**. The mechanism involves the activation of the **mineralocorticoid receptor** by aldosterone, resulting in increased sodium reabsorption in the collecting duct.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it is not directly related to the pathophysiology of hypertension with hypokalemia.
**Option B:** Incorrect as it does not typically present with hypokalemia.
**Option C:** Incorrect because, although it can cause hypertension, it is not classically associated with hypokalemia.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that **primary aldosteronism** is a common cause of secondary hypertension and can be suspected in patients with resistant hypertension or hypokalemia.

**Correct Answer:** D. Primary aldosteronism.