**Core Concept**
Leukotriene receptor antagonists (LTRAs) are a class of medications used to control symptoms of asthma by blocking the action of leukotrienes, which are pro-inflammatory mediators involved in bronchospasm and inflammation.

**Why the Correct Answer is Right**
Montelukast, a cysteinyl leukotriene receptor 1 (CysLT1) antagonist, works by competitively inhibiting the action of leukotrienes at CysLT1 receptors on the surface of airway smooth muscle cells, bronchial epithelial cells, and eosinophils. This inhibition reduces bronchospasm, inflammation, and mucus production, thereby providing relief from asthma symptoms. The CysLT1 receptor is the primary target for LTRAs, and its inhibition is essential for the therapeutic effects of these medications.

**Why Each Wrong Option is Incorrect**
* **Option A:** Zafirlukast is another leukotriene receptor antagonist, but it is not the most commonly used medication for bronchial asthma.
* **Option B:** This option is missing, please provide the actual options for this question.
* **Option C:** This option is missing, please provide the actual options for this question.
* **Option D:** This option is missing, please provide the actual options for this question.

**Clinical Pearl / High-Yield Fact**
LTRAs like montelukast are often used as add-on therapy to inhaled corticosteroids in patients with moderate to severe asthma, as they can help reduce symptoms and improve lung function.

**Correct Answer:** B. Zafirlukast