Answer:
C) Attempted murder by mail bomb
Explanation:
Federal crimes are committed against the nation's laws and institutions, and are out of the jurisdiction of cities and states. In the US, the postal system is federally administrated and a mail bomb would be a federal crime since it's using a federal institution to attempt to commit a crime. Public parks, private homes and police departments are under state or city jurisdiction, so they wouldn't reach the federal level unless appealed several times.
