Which of the following is a good way to set a memory reservation?

A、Usereservationsonallvirtualmachinestoensurethattheyareallguaranteedmemory.
B、Setareservationtoavirtualmachine’savailablememorytoavoidcreatingaswapfile.
C、Neversetareservationonavirtualmachine.
D、Setareservationonlyonacriticalvirtualmachine,withthereservationsettotheminimumamountofmemoryneededforacceptableperformance.