A control unit produces the timing and control signals that carry out each instruction, and it can be built in two ways: as fixed hardwired logic or as stored microcode (microprogrammed).

In a microprogrammed control unit, the control logic is stored as microinstructions in a control memory, so the standout advantage is ease of instruction set updates: adding or changing an instruction only requires rewriting the microprogram, not redesigning hardware.

This stored-microcode approach makes the design flexible and easy to modify or correct, which is its primary architectural benefit over the hardwired style.

A hardwired control unit is built from fixed combinational logic circuits, so any change to the instruction set means physically redesigning that circuitry — the opposite of flexible.

Hardwired control is generally faster because signals come directly from gates rather than from reading control memory, so faster execution is a strength of the hardwired design, not the microprogrammed one.

Lower power consumption and a reduced gate count are likewise typically associated with the simpler hardwired implementation, not with microprogramming.

Hence the distinctive advantage of a microprogrammed control unit is its flexibility, making the correct answer Ease of instruction set updates.