**Core Concept**
Leukotriene antagonists are a class of medications that block the action of leukotrienes, which are pro-inflammatory mediators involved in the pathogenesis of asthma and other inflammatory diseases. These compounds bind to leukotriene receptors, specifically the cysteinyl leukotriene receptor 1 (CysLT1), thereby inhibiting the bronchoconstrictive and inflammatory effects of leukotrienes.

**Why the Correct Answer is Right**
Montelukast is a selective cysteinyl leukotriene receptor 1 (CysLT1) antagonist that inhibits the action of leukotrienes in the airways. By blocking the CysLT1 receptor, montelukast reduces the bronchoconstrictive effects of leukotrienes, making it an effective treatment for asthma and other inflammatory conditions. This mechanism of action is distinct from corticosteroids and beta-agonists, which work through different pathways to control airway inflammation and constriction.

**Why Each Wrong Option is Incorrect**
**Option A:** Zafirlukast is a leukotriene receptor antagonist, but it is not the most commonly used or well-known compound in this class. While zafirlukast does work by blocking the action of leukotrienes, it is not the primary example of a leukotriene antagonist.
**Option B:** Fluticasone is a corticosteroid used in the treatment of asthma and other inflammatory conditions. While it is effective in controlling airway inflammation, its mechanism of action is distinct from that of leukotriene antagonists.
**Option C:** Salmeterol is a long-acting beta-agonist (LABA) used in combination with inhaled corticosteroids to control asthma symptoms. Its mechanism of action is also different from that of leukotriene antagonists.

**Clinical Pearl / High-Yield Fact**
It is essential to remember that leukotriene antagonists like montelukast can be used as add-on therapy to inhaled corticosteroids in patients with uncontrolled asthma. This combination can provide additional benefits in controlling symptoms and improving lung function.

**Correct Answer:** C. Montelukast