During James Monroe's presidency, the Supreme Court, particularly through cases like McCulloch v. Maryland (1819), expanded the power of the federal government by affirming its ability to regulate the economy and establish a national bank. This decision supported the idea of implied powers under the Necessary and Proper Clause of the Constitution, which allowed the federal government to take actions not explicitly outlined in the Constitution, as long as they were in pursuit of its constitutional powers. Therefore, the correct answer is:
It gave the federal government power to regulate the economy.