Undefined (not a real number)
The square root of -256 would result in an imaginary number so by terms, it's "not real". The imaginary number would be 16i. 16x 16 =256, but since it's negative, it's √16 √16i.
Answer:
C and D are same options
(D)
Step-by-step explanation:

It’s B actually :) hope this helps