A memory--memory, machine instruction for a certain machine has the following format. (Such an instruction is similar to a register—register instruction except that the operands are displaced addresses in memory.) Which of the following could be an assembly language instruction that would be translated into a memory—to—memory instruction for this machine( ).

A．ADD 10(R1) ,20(R2)

B．ADD(10R1), (20R2)

C．ADD R1,10(R2),20

D．ADD R1,10,20(R2)