Final answer:
A healthy 10-year-old boy diagnosed with acute sinusitis should be prescribed amoxicillin, as it is the first-line antibiotic for this condition.
Step-by-step explanation:
A 10-year-old healthy boy diagnosed with acute sinusitis should initially be prescribed amoxicillin. Amoxicillin is a commonly prescribed antibiotic for bacterial infections and is the first-line drug when treating acute sinusitis in children who are otherwise healthy. Given that high-dose amoxicillin is effective in the early stages of bacterial infections, it would be the appropriate choice. Ceftriaxone is typically reserved for more severe or complicated cases, or in patients who have not responded to initial treatments with other antibiotics. Prednisolone, a corticosteroid, and ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), can be used to manage symptoms, but they do not treat the underlying bacterial infection.