The Supremacy Clause played a key role in McCulloch v. Maryland by holding that:

• A. Federal law is supreme over state law.
• B. States may tax federal institutions if they have the power.
• C. The Constitution requires all banks to be chartered by the federal government.
• D. The Tenth Amendment reserves powers to the states.

Answer: (A)

The key idea is that federal law and the Constitution take precedence over state law when there’s a conflict. In McCulloch v. Maryland, the Supreme Court reinforced that the national government can use implied powers to carry out its constitutional duties, such as creating a national bank, under the Necessary and Proper Clause. Because the federal action is within those powers, a state cannot undermine it by imposing a tax on the federal institution; doing so would place state interests above federal authority, which the Supremacy Clause prohibits. So the ruling characterizes federal law as supreme over state laws. The other options misstate the relationship: taxing a federal instrument by a state is not allowed, the Constitution does not require all banks to be federally chartered, and the Tenth Amendment concerns reserved powers rather than establishing federal supremacy.