Final answer:
Annual advancement exams for ranks E-4 through E-6 in the United States Navy are typically held in March and September for active-duty personnel, with reservists taking them in February for E-4/E-5 and in August for E-6.
Step-by-step explanation:
The annual advancement exams for sailors in the United States Navy who are seeking promotion to the ranks of E-4 through E-6 are typically administered twice a year. For active-duty personnel, semi-annual exams are held in March for the E-4 to E-6 paygrades, and in September for the E-6 paygrade. For reservists, the exams typically occur in February for E-4 and E-5 paygrades, and in August for E-6. It's crucial to stay informed through official Navy communications for accurate dates as they can occasionally vary or shift due to operational considerations or changes in policy.