Question

nca civilization was structured as

a coalition of independent city-states.
a large empire with one ruler.
tribes unified under one religion.
tribute states under a central authority.

Answer 1

Likely you mean the Inca. The Inca civilization was structured as a large, centralized empire ruled by a single supreme ruler (the Sapa Inca), though conquered regions were incorporated and required to provide labor/tribute to the central state.