Consider a processor that includes a base with any addressing mode. Let the address stored in the program counter be designed by the symbol x1. The instruction stored in x1 has an address part (operand reference) x2. The operand needed to execute the instruction is stored in the memory word with address x3. An index register contains the value x4. Currently the base contains x5. what is the relationship between these various quantities if the addressing mode of the instruction is: a) Direct b) Indirect c) PC relative d) Indexed