Final answer:
Congress is the organization that sets the size of the Supreme Court.
Step-by-step explanation:
The organization that sets the size of the Supreme Court is Congress, which is the legislative branch of the United States government. According to the Constitution, the size of the Supreme Court is not specified, but Congress has the power to determine the number of justices. Currently, there are nine justices on the Supreme Court, but this number has changed throughout history.
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