**Core Concept**
Triamterene is a potassium-sparing diuretic that acts on the collecting ducts of the kidneys to increase sodium and water excretion. It works by inhibiting the epithelial sodium channel (ENaC) and reducing the reabsorption of sodium.

**Why the Correct Answer is Right**
Triamterene's mechanism of action involves blocking the ENaC, which leads to a decrease in sodium reabsorption in the collecting ducts. This results in increased sodium and water excretion in the urine, while also allowing potassium to be reabsorbed. This is because the sodium gradient across the collecting ducts is reduced, leading to a decrease in the activity of the Na+/K+-ATPase pump, which in turn reduces potassium secretion.

**Why Each Wrong Option is Incorrect**
**Option A:** This is not a known effect of triamterene.
**Option B:** Triamterene does not increase blood pressure; in fact, it is used to treat hypertension.
**Option C:** This is not a direct effect of triamterene.

**Clinical Pearl / High-Yield Fact**
Triamterene can cause hyperkalemia as a side effect due to its potassium-sparing action. Monitor potassium levels closely when using this medication.

**Correct Answer:** B. Triamterene is used to treat hypertension.