单选题：Which one of the following statements is correct about synchroni
Which one of the following statements is correct about synchronization primitives ?@[B](1)
A. The primitive could be implemented by disabling interrupts, even in single-processor systems.
B. The primitive could not implemented by disabling interrupts, neither in single-processor systems nor in multiprocessor systems.
C. The primitive could only be implemented by disabling interrupts for multiprocessor systems.
D. If used in user-level programs, the primitive could be implemented by disabling interrupts.
A.The primitive could be implemented by disabling interrupts, even in single-processor systems.
B.The primitive could not implemented by disabling interrupts, neither in single-processor systems nor in multiprocessor systems.
C.The primitive could only be implemented by disabling interrupts for multiprocessor systems.
D.If used in user-level programs, the primitive could be implemented by disabling interrupts.
答案：B
A. The primitive could be implemented by disabling interrupts, even in single-processor systems.
B. The primitive could not implemented by disabling interrupts, neither in single-processor systems nor in multiprocessor systems.
C. The primitive could only be implemented by disabling interrupts for multiprocessor systems.
D. If used in user-level programs, the primitive could be implemented by disabling interrupts.
A.The primitive could be implemented by disabling interrupts, even in single-processor systems.
B.The primitive could not implemented by disabling interrupts, neither in single-processor systems nor in multiprocessor systems.
C.The primitive could only be implemented by disabling interrupts for multiprocessor systems.
D.If used in user-level programs, the primitive could be implemented by disabling interrupts.
答案：B