WASHINGTON — The U.S. Supreme Court heard a potentially significant antitrust case Monday to decide whether Apple can be sued for using its monopoly power over its iPhones to profit from the sale of apps.Lawyers for the Trump administration joined with Apple in urging the high court to throw out the case, but they ran into skeptical questions from most of the justices.“This is a closed loop,” Justice Sonia Sotomayor told a lawyer for Apple.