**Core Concept**
The question is testing the management of acute symptoms of hyperthyroidism, specifically the control of tachycardia and palpitations. This involves understanding the pathophysiology of hyperthyroidism and the pharmacological interventions used to manage its symptoms.

**Why the Correct Answer is Right**
Beta-blockers, such as propranolol, are used to control the symptoms of hyperthyroidism, including tachycardia and palpitations. They work by blocking the effects of epinephrine on the heart, thereby reducing heart rate and contractility. Propranolol is a non-selective beta-blocker that blocks both beta-1 and beta-2 receptors, which are responsible for the cardiac and smooth muscle effects of epinephrine, respectively.

**Why Each Wrong Option is Incorrect**
**Option A:** **Metoprolol** is a selective beta-1 blocker that is primarily used to manage hypertension and angina. While it can control heart rate, it is not the first choice for managing hyperthyroidism symptoms.
**Option B:** **Diltiazem** is a calcium channel blocker that is primarily used to manage hypertension and angina. It can slow heart rate, but it is not the preferred agent for managing hyperthyroidism symptoms.
**Option C:** **Amlodipine** is a calcium channel blocker that is primarily used to manage hypertension. It has no significant effect on heart rate or palpitations.

**Clinical Pearl / High-Yield Fact**
Beta-blockers, such as propranolol, are the first-line treatment for controlling tachycardia and palpitations in persons with acute symptoms of hyperthyroidism. They should be used in conjunction with other treatments, such as antithyroid medications, to manage the underlying condition.

**Correct Answer:** C. Propranolol