The central bank of the united states is called the:

a) bank of the united states system.
b) federal reserve system.
c) federal bank oversight system.
d) credit reserve system.

Option B.

Explanation:

Federal Reserve System, is the right answer.

The central banking system of the U.S. is the Federal Reserve System. This system was created on 23rd December 1913 by the Federal Reserve Act, following a set of economic crashes directed to the appetite for central administration of the financial system to mitigate financial emergencies. Over the course of time, the Great Depression and the  Great Recession led to the extension of the roles and responsibilities of this System.