Solution

Micro operation means elementary operation performed on data stored in register.

So, (a) $\rightarrow$ (iv)

Micro programmed control unit uses control memory.

So, (b) $\rightarrow$ (iii)

Interrupts improve CPU utilization because CPU need not wait continuously for I/O operations.

So, (c) $\rightarrow$ (ii)

Micro instruction specifies micro operations.

So, (d) $\rightarrow$ (i)

Hence, correct matching is:

$(a)-(iv),\ (b)-(iii),\ (c)-(ii),\ (d)-(i)$