Final answer:
An unfunded mandate is when the federal government requires states to follow regulations without providing the necessary funding. The correct answer to the question is C. unfunded mandate.
Step-by-step explanation:
When the federal government requires state governments to comply with specific regulations without providing financial compensation for those costs, it is referred to as a unfunded mandate. Unlike grants-in-aid or block grants which come with federal funding to support state and local governments, unfunded mandates place the fiscal responsibility on state and local entities to satisfy these federal demands. This compulsion often aims to promote national objectives across various policy areas but may result in financial strain for states that must find resources to implement these directives. Therefore, the correct answer to the student's question is C. unfunded mandate.