Final answer:
b. The national government is supreme.
The supremacy clause in the Constitution ensures that the national government is the supreme authority over the state governments, particularly when federal and state laws conflict. State governments do have their own powers, but these do not supersede federal law.
Step-by-step explanation:
One key difference between national and state government in the United States is the principle of supremacy. According to the supremacy clause found in Article VI of the Constitution, the national government is supreme when it comes to the Constitution and federal laws. This means that if there is a conflict between state law and federal law, federal law will prevail. Conversely, the state governments have their own set of powers, often referred to as reserved powers, which they can exercise independently unless specifically denied by the Constitution. For example, states take the lead in matters like education and local transportation, which are not enumerated powers of the federal government. Additionally, there are concurrent powers such as the power to tax, which both the national government and the states possess and can exercise simultaneously.