Final answer:
A federal court in the U.S. has jurisdiction over a case when it involves federal law, diversity of citizenship with an amount over $75,000, or certain specialized areas like cases involving foreign governments or states. The correct option is b)When the matter involves federal law.
Step-by-step explanation:
In the United States, a federal court has jurisdiction over a case when the matter involves the application or interpretation of federal law, which includes cases where there is a 'federal question' involving the U.S. Constitution, federal laws, or treaties.
Additionally, federal courts have jurisdiction in cases where both parties are from different states, known as diversity of citizenship, and the amount in controversy exceeds $75,000. Cases involving foreign governments, patent infringement, Native American rights, maritime law, bankruptcy, or controversies between two or more states are also within the federal court's jurisdiction.
However, when a case involves citizens from the same state, the federal court typically does not have jurisdiction, unless there is a federal question. If a state court refuses to hear a case, it does not automatically confer jurisdiction to the federal courts. The correct option is b)When the matter involves federal law.