Question

which is the best definition for empire?
a government in which a single ruler makes and enforces the laws of the land
a region where a people have developed certain characteristics, such as government and trade
an area or political unit in which formerly independent states are under the control of one ruler
an area where independent states join together for the purpose of trade but retain self - rule

Explanation:

An empire is typically a political unit where formerly independent states are under the control of one ruler. A single - ruler government is more like an autocracy. A region with certain characteristics is a general cultural or geographical area. States joining for trade while retaining self - rule is more like a trade confederation.

Answer:

an area or political unit in which formerly independent states are under the control of one ruler