During James Monroe's presidency, the U.S. Supreme Court, under Chief Justice John Marshall, played a significant role in shaping the power and authority of the federal government. The correct answer is:
C. the court expanded the power of the federal government by making it easier for the government to regulate trade.
John Marshall's decisions often reinforced federal authority over states and established important principles regarding federalism, including the regulation of interstate commerce and the supremacy of federal laws. Key cases like Gibbons v. Ogden (1824) clarified the federal government's authority to regulate interstate commerce, thereby expanding its power.