The correct answer is appeals from state courts and federal courts.
The Supreme Court is the highest court in the land, and it safeguards that the majority’s opinion, that usually tend to change in time, do not demoralize the principal values of the American culture, such as freedoms, due process of law, etc. Most of the Supreme Courts cases are heard on appeal from the courts previously named. If someone from those courts wish their case to be heard in the Supreme Court, they must file for a writ of certiorari, later if at least 4 of 9 justices from the Supreme court decide to issue a writ, then their case can be heard in the highest court.
