Answer:
B. voter registration requirements have usually been set by the states
Step-by-step explanation:
In United States, voter registration requirements have usually been set by the state. The requirements ranges from age, to registration deadline, thus, different states has its laws and rule, which serves as the basic requirements to vote.
Also, since Elections are state-by-state contests and because of differences in political cultures from state to state, the process of voter registration varies.