..............prefix in x86 ISA specifies that an instruction executes automatically in a multiprocessor system.   (1 Point)SIBreplockNone of these

The correct answer to the question regarding which prefix in the x86 Instruction Set Architecture (ISA) specifies that an instruction executes automatically in a multiprocessor system is:

rep lock

The "rep lock" prefix is used to ensure that the instruction it precedes is atomic in multiprocessor environments, preventing other processors from accessing the memory location during its execution. This is crucial for maintaining data consistency when multiple processors might be accessing shared resources. Thus, it provides necessary synchronization for multi-threaded applications.

In summary, "rep lock" is the required prefix for automatic execution in multiprocessor systems in x86 ISA.