An instruction is made up of operations that (68) the function to be performed and operands that represent the data to be operated on. For example, if an instruction is to perform the operation of (69) two numbers, it must know (70) the two numbers are. The processor’s job is to (71) instructions and operands from memory and to perform each operation. Having done that, it signals memory to send it (72) instruction.
A．first
B．last
C．next
D．second
创伤下列哪一项是正确的（）。