**Core Concept**
Beta-blockers are a class of medications that inhibit the effects of the sympathetic nervous system on the heart, reducing heart rate and contractility. In hyperthyroidism, the increased sympathetic tone and elevated circulating catecholamines lead to tachycardia and palpitations.

**Why the Correct Answer is Right**
Propranolol, a non-selective beta-blocker, is the preferred choice for controlling tachycardia and palpitations in acute hyperthyroidism. It blocks the beta-1 and beta-2 adrenergic receptors, thereby reducing heart rate and contractility. This helps alleviate symptoms of hyperthyroidism, such as tachycardia, palpitations, and tremors. Propranolol also has a mild anti-adrenergic effect, which helps counteract the increased sympathetic tone associated with hyperthyroidism.

**Why Each Wrong Option is Incorrect**
**Option A:** Digoxin is a cardiac glycoside that increases the force of cardiac contractions, which is not ideal for managing tachycardia and palpitations in hyperthyroidism.
**Option B:** Metoprolol is a selective beta-1 blocker that is effective for hypertension and angina, but may not be as effective as propranolol for controlling symptoms of hyperthyroidism.
**Option C:** Atenolol is another selective beta-1 blocker that has a longer half-life than metoprolol, but shares similar limitations for managing hyperthyroidism symptoms.

**Clinical Pearl / High-Yield Fact**
Beta-blockers like propranolol can precipitate bronchospasm in patients with asthma, so it's essential to monitor for signs of bronchospasm and adjust the treatment plan accordingly.

**Correct Answer: C. Propranolol**