Which type of addressing mode, less number of memory references are required?

Answer: Immediate addressing

Explanation:

Immediate addressing places the operand value directly inside the instruction word. As a result, the CPU only needs to fetch the instruction (which is always required) and does not need any additional memory reference to obtain the operand.

• Immediate: Operand encoded in the instruction, so no separate memory access for the operand.

• Register: Operand in CPU registers, so the instruction does not fetch from memory during execution, but the register may have been loaded earlier from memory.

• Implied: Uses implicit operands (for example, accumulator) and typically avoids fetching an operand from memory at execute time, but the actual literal operand is not part of the instruction as in immediate addressing.

• Indexed: Requires computing an effective address and then accessing memory to fetch the operand, so it involves additional memory references.

Therefore, immediate addressing is the best answer because it guarantees that no extra memory reference is needed to obtain the operand beyond the instruction fetch.