Answer:
A. Identify the jurisdiction of federal courts
Step-by-step explanation:
This excerpt talks exclusively about the Judicial Branch of the U.S. government, that is, federal courts, so we can discard options B and C. Neither does it deal with the limits of the federal courts, as it only talks about what they can do. The purpose of this passage, then, is to identify the jurisdiction of federal courts. It gives them the authority to hear cases related to the US Constitution, laws derived from it and to US treaties with other nations.