Question

Most cases in the U.S. Supreme Court are accepted by

Answer 1

in forma pauperis

writ of certiorari

courts of appeal

district courts

Answer 2

Writ of certiorari. The Supreme Court need not review every decision by US Courts of Appeal, and in fact reviews very few. The losing side in the Court of Appeals must ask the SCOTUS to review the case, and present an argument of why it should.