## **Core Concept**
Calcium channel blockers (CCBs), particularly dihydropyridines like **nifedipine**, commonly cause **ankle edema** as a side effect. This occurs due to vasodilation of peripheral arterioles, leading to increased hydrostatic pressure and fluid leakage into the interstitial space.

## **Why the Correct Answer is Right**
The correct answer, **ACE inhibitors** (or **angiotensin-converting enzyme inhibitors**), can prevent or reduce ankle edema caused by CCBs. ACE inhibitors work by blocking the conversion of **angiotensin I** to **angiotensin II**, a potent vasoconstrictor. By reducing angiotensin II levels, ACE inhibitors promote vasodilation and decrease peripheral resistance. When used in combination with CCBs, ACE inhibitors can mitigate the vasodilatory effects that lead to ankle edema.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option is blank and does not provide a viable choice for preventing ankle edema caused by CCBs.
* **Option B:** This option is also blank and does not offer a valid alternative.
* **Option D:** Similarly, this option is blank and lacks a relevant choice.

## **Clinical Pearl / High-Yield Fact**
A useful clinical strategy to manage or prevent CCB-induced ankle edema is to combine these agents with **ACE inhibitors** or **angiotensin receptor blockers (ARBs)**, which can counteract the localized vasodilatory effects. This combination is not only effective in reducing edema but also provides additional cardiovascular benefits.

## **Correct Answer:** .