**Core Concept**
Leukotriene antagonists are a class of medications used to treat asthma and other respiratory conditions by blocking the action of leukotrienes, which are substances in the body that cause inflammation and constriction of airways.

**Why the Correct Answer is Right**
Montelukast is a specific leukotriene receptor antagonist that works by binding to cysteinyl leukotriene receptors (CysLT1 receptors) on smooth muscle cells in the airways, preventing the constriction and inflammation caused by leukotrienes. This results in improved lung function and reduced symptoms of asthma. Montelukast also inhibits the production of leukotrienes by blocking the 5-lipoxygenase pathway.

**Why Each Wrong Option is Incorrect**
* **Option A:** Zafirlukast is also a leukotriene receptor antagonist, but it is not the correct answer since the question is likely testing for a more well-known or commonly used medication.
* **Option B:** Salmeterol is a long-acting beta-2 adrenergic receptor agonist (LABA) used in the maintenance and control of asthma symptoms, but it is not a leukotriene antagonist.
* **Option D:** Fluticasone is an inhaled corticosteroid used to control and prevent asthma symptoms, but it is not a leukotriene antagonist.

**Clinical Pearl / High-Yield Fact**
Leukotriene antagonists like montelukast can be used as add-on therapy to inhaled corticosteroids for patients with persistent asthma who are not adequately controlled with inhaled corticosteroids alone.

**Correct Answer:** C. Montelukast