**Core Concept**
β-blockers are a class of medications that can exacerbate asthma by blocking β2-adrenergic receptors in the airways, leading to bronchoconstriction. However, some β-blockers are safer in asthma patients due to their selective β1-receptor blockade with minimal β2-receptor blockade.

**Why the Correct Answer is Right**
The β-blocker that is safe in asthma is **Non-selective β-blockers are generally contraindicated in asthma**, but among the selective β1-blockers, **Metoprolol** is considered safe due to its negligible β2-receptor blockade. Metoprolol has a higher intrinsic sympathomimetic activity (ISA) which may contribute to its safety in asthma. Additionally, its lipophilic nature allows it to penetrate the heart more efficiently, reducing peripheral β2-receptor blockade.

**Why Each Wrong Option is Incorrect**
**Option A:** Propranolol - This non-selective β-blocker is contraindicated in asthma due to its significant β2-receptor blockade, which can worsen bronchospasm.
**Option B:** Atenolol - Although a selective β1-blocker, atenolol has a higher risk of bronchoconstriction in asthma patients due to its hydrophilic nature and limited ISA.
**Option C:** Nadolol - This lipophilic β-blocker has significant β2-receptor blockade, making it unsuitable for asthma patients.

**Clinical Pearl / High-Yield Fact**
When prescribing β-blockers to asthma patients, always consider the patient's asthma severity and the specific β-blocker's pharmacological profile to minimize the risk of bronchoconstriction.

**Correct Answer: C. Nadolol**