## **Core Concept**
The question tests the understanding of drugs that can precipitate an acute attack of asthma. Asthma is a chronic inflammatory disease of the airways characterized by recurring episodes of reversible airflow obstruction. Certain medications can trigger or worsen asthma symptoms.

## **Why the Correct Answer is Right**
Propranolol, a non-selective beta-blocker, can precipitate an acute attack of asthma. This is because it blocks beta-2 receptors in the lungs, which are responsible for bronchodilation. By blocking these receptors, propranolol can cause bronchoconstriction, leading to an asthma attack. On the other hand, **salbutamol (also known as albuterol)**, is a short-acting beta-2 agonist that is commonly used to relieve asthma symptoms by inducing bronchodilation.

## **Why Each Wrong Option is Incorrect**
* **Option A:** **Aspirin** can precipitate an acute attack of asthma, particularly in patients with aspirin-exacerbated respiratory disease (AERD). Aspirin inhibits cyclooxygenase enzymes, which can lead to a shift in the production of eicosanoids towards more bronchoconstrictive leukotrienes.
* **Option B:** **Propranolol**, as discussed, can precipitate an acute asthma attack by blocking beta-2 adrenergic receptors.
* **Option C:** **Indomethacin**, another nonsteroidal anti-inflammatory drug (NSAID), similar to aspirin, can also precipitate asthma attacks in susceptible individuals by a similar mechanism.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that patients with asthma should avoid NSAIDs, including aspirin and indomethacin, due to the risk of triggering an asthma attack. Beta-2 agonists like **salbutamol** are lifesavers in acute asthma attacks.

## **Correct Answer:** . Salbutamol