Final answer:
The first-line treatment for acute otitis media in a patient without drug allergies is amoxicillin 500 mg PO TID for 5-7 days.
Step-by-step explanation:
The first-line treatment for acute otitis media (AOM) in a patient without any known drug allergies is high-dose amoxicillin. Therefore, the correct answer is a. Amoxicillin 500 mg PO TID (three times a day) for 5-7 days. This antibiotic is commonly prescribed for ear infections due to its effectiveness against the typical bacteria that cause AOM, and it is generally well-tolerated. However, if symptoms persist or if there is treatment failure, alternatives such as macrolides or cephalosporins may be considered.