What is the purpose of the direct addressing mode by register?


a) It allows the execution of real mode applications that violate the rules under the control of a protected mode operating system.
b) It is a mode of operation launched with the Intel 386SL processor, in which all normal execution is suspended and a special software is executed in a high privilege mode.
c) It is a mode in the AMD64 architecture where a 64-bit application or operating system can access the 64-bit instructions and registers of the processor.
d) It is a mode of addressing where the operand is specified with direct addressing by register, meaning that the operand resides in one of the processor registers selected by a register field in the instruction.