Final answer:
Categorical grants are funds from the national government to states for specific purposes with strings attached, requiring adherence to strict criteria.
Step-by-step explanation:
The grants given to the states by the national government that can only be used for a specific purpose are known as categorical grants. These grants come with conditions or "strings attached" that strictly define how the funds must be used and usually require states to meet specific criteria or provide matching funds. Categorical grants are differentiated from block grants, which are more general and come with fewer restrictions. They are an important tool for the national government to influence state and local policy to align with national objectives.