Answer: Federal (national)
Step-by-step explanation:
In the united state, the dual banking system is one of the type of banking system which include both the national and the state banks.
In the dual banking system, the national banks are basically regulated or controlled by the federal law and regulation and then also supervised by the federal agency.
The importance of this dual banking system is that it is necessary for maintaining the balance between the state and the national banks and also providing the various types of benefits to the system.
Therefore, Federal or the national banks is the correct answer.