Which Property of Mutual Exclusion Primitives Is Inappropriate for Multiprocessor

Which property of mutual exclusion primitives is inappropriate for multiprocessor systems?

A) The solution is implemented purely in software on a machine without specially designed mutual exclusion machine-language instructions.
B) No assumption can be made about the relative speeds of asynchronous concurrent threads.
C) A thread that is executing instructions outside its critical section cannot prevent any other threads from entering their critical sections.
D) A thread must not be indefinitely postponed from entering its critical section.