The government of Mexico is a federal republic. What does this mean?

Aseparate states can govern themselves
Bgovernment is under one central authority
Cseparate states unite under one government
Da single person has power in the government

Verified Answer :

A Federal Republic is a system in which a country is a federation of partially independent states (in Mexico those are for example Estado de Mexico, Oacaca...) but these states unite under one central government. This central government deals for example with foreign relations.  

The correct answer is: c. separate states unite under one government