Microprogrammed control unit:
(a) is wrong. Microprogrammed CU can never be faster than hardwired CU. Microprogrammed CU it has an extra layer on top of hardwired CU and hence can only be slower than hardwired CU.
(b) is a suitable answer as we can add new instruction by changing the content of control memory.
(c) is not correct as when only small programs are there, hardwired control makes more sense.
(d) control unit can also be hardwired, so this is also not correct.
The link is dead. For small programs, why Hardwired?
Is it because only few hardware devices are needed. And in Case of Microprogrammed, circuit complexity remains same for small programs too.