Final answer:
The most appropriate treatment for a 9 year-old patient with allergic rhinitis symptoms and persistent nasal congestion, sneezing, rhinorrhea, and eczema would be immunotherapy (Option C).
Step-by-step explanation:
The most appropriate treatment for a 9 year-old patient with allergic rhinitis symptoms and persistent nasal congestion, sneezing, rhinorrhea, and eczema would be immunotherapy (Option C). Immunotherapy, also known as allergy shots, involves gradually exposing the patient to larger amounts of allergens to desensitize the immune system and reduce symptoms. This method has been found to be particularly effective for allergies to pollen and insect stings. Other treatment options mentioned in the question such as antihistamines (Option B), topical corticosteroids (Nasarel), and antileukotriene drugs (montelukast) may provide relief for milder symptoms, but in this case, as the symptoms are persistent and not well-controlled, immunotherapy would be the most appropriate next step.