The undefined nuclear region of prokaryotes are also known as
(a) nucleus
(b) nucleolus
(c) nucleic acid
(d) nucleoid.

Correct Answer: (d) nucleoid.

Explanation:

A prokaryote is a unicellular organism with a primitive type of nucleus, which is an undefined nuclear region known as a nucleoid. Prokaryotic cell lacks a membrane-bound nucleus, mitochondria, and any other membrane-bound organelle.