Correct Answer: A

Rationale: Loratadine is a second-generation antihistamine that selectively blocks peripheral histamine H1 receptors. By preventing histamine binding, it alleviates allergic symptoms such as sneezing, rhinorrhea, and itching without significant sedation because it poorly crosses the blood-brain barrier. Its mechanism does not involve direct inhibition of mast cell degranulation or leukotriene synthesis. The clinical improvement in allergic rhinitis after administration demonstrates effective peripheral receptor antagonism, making Loratadine a preferred non-sedating antihistamine.

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