Final answer:
In a strong-mayor city system, the mayor has substantial executive authority, including the power to appoint major department heads.
Step-by-step explanation:
In a strong-mayor city system, the mayor-council structure of government is such that the mayor holds significant executive power. Among these powers, the mayor has the authority to veto the actions of the council, appoint and remove the heads of city departments, and produce a city budget. Thus, in a strong-mayor city, the mayor would indeed appoint major department heads, unlike in a council-manager system where the city manager would be tasked with carrying out the administrative functions.