Question

government positions under hongwu were filled by
appointment.
election.
civil service exams.
officers in the military.

Explanation:

During the Hongwu Emperor's reign in the Ming Dynasty, government positions were filled through civil service exams (the imperial examination system). Appointments without exams, elections (not a common method then), or only military officers were not the primary way. The civil service exam system was used to select officials based on their knowledge of Confucian classics and administrative skills.

Answer:

civil service exams.