In which addressing mode is the operand given explicitly within the…

An addressing mode is the rule by which the CPU determines where an instruction's operand actually comes from: the value itself, a memory address, a pointer to an address, or an address computed from a base and an offset/index.

1. Immediate mode: the operand's constant value is placed directly inside the instruction word, so the CPU reads it straight from the instruction with zero extra memory references.

2. Absolute (direct) mode: the instruction instead carries the memory address of the operand, so one memory access is needed to fetch the value stored there.

3. Indirect mode: the instruction carries the address of a location that itself stores the operand's address, so two memory accesses are needed to resolve the final value.

4. Index mode: the effective address is computed by adding an index register's content to a base/displacement given in the instruction, followed by a memory access at that computed address.

Only immediate mode requires no memory access at all to obtain the operand, because the value is already present in the instruction. Absolute, indirect, and index modes all require at least one memory reference to compute or fetch the operand. Hence the operand being 'given explicitly in the instruction itself' uniquely identifies immediate mode.

Immediate mode is the correct answer.