The instruction LD ADR(X) which is equivalent to AC ← M[ADR + XR] is in :

Correct option is C

In index addressing mode, the effective address of the operand is obtained by adding a constant value (ADR) to the contents of an index register (XR). This mode is typically used for accessing array elements. The instruction LD ADR(X) loads the accumulator (AC) with the value from the memory address ADR + XR.