The statement that is true about the Supreme Court is:
The Supreme Court hears cases that have already been heard in lower courts.
The Supreme Court typically reviews cases that have been decided by lower courts (either state or federal) and can hear appeals on those cases, usually involving significant legal or constitutional questions. The other statements are not accurate. The Supreme Court does not refer veterans' claims to military courts, does not primarily focus on tax cases, and does not hear cases directly from district courts.