B. Only federal courts handle cases between citizens of different states.
Step-by-step explanation:
State courts only work with cases within that same state, like family courts, as they are governed by the state. Many smaller cases will be taken care of by state or local courts.
Federal courts work with cases with citizens of different states. These courts also work with certain federal laws and cases that are usually against the United States. Federal courts usually work on bigger cases that aren't for state courts.