Which Is an Example of a Federal Mandate

Which is an example of a federal mandate?

A) Congress passes a law requiring all nuclear power plants to revise and strengthen their safety protocols.
B) Congress passes a law requiring all states to adopt a sex offender registry system categorizing offenders based on conviction,not future threat.
C) The Environmental Protection Agency sends money to Louisiana to help with cleanup from the gulf oil spill.
D) The Nevada legislature passes a law requiring all public school teachers to spend twenty hours per week preparing students for the state achievement test.