The two word instruction is stored in memory at an address designated by symbol $W .$ The address field of the instruction (stored at $W+1$ ) is designated by the symbol $Y$. The operand used during the execution of the instruction is stored at address symbolized by $Z$. An index register contains the value $X$. State how $Z$ is calculated from the other addresses if the addressing mode of the instruction is
(A) Direct
(1) $Z=\operatorname{Mem}(Y)$
(B) Indirect
(2) $\quad Z=Y+W+2$
(C) Relative
(3) $Z=Y+X$
(D) Indexed
(4) $\quad Z=Y$
(A) $\mathrm{A}-4, \mathrm{~B}-1, \mathrm{C}-2, \mathrm{D}-3$
(B) $\mathrm{A}-3, \mathrm{~B}-1, \mathrm{C}-2, \mathrm{D}-4$
(C) $\mathrm{A}-4, \mathrm{~B}-2, \mathrm{C}-1, \mathrm{D}-3$
(D) $\mathrm{A}-3, \mathrm{~B}-2, \mathrm{C}-1, \mathrm{D}-4$
Computer Organization and Architecture
Machine Instructions, Addressing Modes