The active medium and long-term interest rate futures in the global futures market include: Chicago Board of Trade 2-year US Treasury futures, 3-year US Treasury futures, 5-year US Treasury futures, 10-year US Treasury futures and long-term US Treasury futures; German bond futures of European exchanges, including short-term German bond futures, medium-term German bond futures and long-term German bond futures; British government long-term government bond futures on the London International Financial Exchange; Australian Stock Exchange Group Sydney Futures Exchange's 3-year Australian government bond futures, etc. So options a, b, c and d are all correct.