Okay, I need to figure out the correct answer for the treatment of Prinzmetal's angina. Let me start by recalling what Prinzmetal's angina is. It's a type of angina caused by coronary artery spasm, right? Unlike typical angina which is due to fixed atherosclerotic plaques, this is more about spasms. So the treatment would target preventing those spasms.

The main drugs for angina are nitrates, beta-blockers, calcium channel blockers. But wait, beta-blockers might not be the best here because they can actually worsen coronary spasm by unopposed alpha-adrenergic activity. So beta-blockers are contraindicated in Prinzmetal's angina. That leaves calcium channel blockers. Specifically, the long-acting ones like nifedipine or verapamil. They relax the coronary vessels, preventing spasm. Also, nitrates like nitroglycerin can be used for acute episodes, but the maintenance treatment is calcium channel blockers.

Looking at the options, if the correct answer is calcium channel blockers, then the other options would be beta-blockers, ACE inhibitors, or maybe others. Let me check the distractors. The question didn't list the options, but the correct answer is calcium channel blockers. So the other options would be incorrect because beta-blockers are contraindicated, ACE inhibitors are for heart failure or hypertension, and maybe ranolazine or something else. Each wrong option needs a reason. The clinical pearl is that calcium channel blockers are key, and beta-blockers are bad here. Let me structure this into the required sections now.

**Core Concept**
Prinzmetal's angina (variant angina) is caused by transient coronary artery spasm, often in the absence of significant atherosclerosis. The treatment focuses on preventing coronary vasospasm, which differs from atherosclerosis-driven angina.

**Why the Correct Answer is Right**
Calcium channel blockers (e.g., nifedipine, verapamil) are the treatment of choice because they inhibit calcium influx into vascular smooth muscle, relaxing coronary arteries and preventing spasm. They also reduce myocardial oxygen demand. Long-acting formulations are preferred for sustained spasm prevention. Nitroglycerin (acute) may be used for relief, but calcium channel blockers remain the cornerstone.

**Why Each Wrong Option is Incorrect**
**Option A:** Beta-blockers may worsen coronary spasm by unopposed alpha-adrenergic stimulation (beta-blockade without alpha-blockade).
**Option B:** ACE inhibitors are ineffective for coronary vasospasm and used for heart failure/hypertension.
**Option D:** Ranolazine is for chronic angina but lacks direct spasmolytic effects and is not first-line.

**Clinical Pearl / High-Yield Fact**
Remember **"Calcium for spasm, beta-blockers for danger"** in Prinzmetal’s angina. Avoid beta-blockers; prioritize calcium channel blockers to prevent life-threatening coronary spasm. Always correlate with ECG changes (ST elevation during episodes) for diagnosis.

**Correct Answer: C. Calcium channel blockers**

✓ Correct Answer: A. Nitroglycerine