Final answer:
The primary organelle that distinguishes a prokaryotic cell from a eukaryotic cell is the nucleoid.
Step-by-step explanation:
A prokaryotic cell is a simple, single-celled organism that lacks a nucleus and other membrane-bound organelles. One of the primary organelles that distinguishes a prokaryotic cell from a eukaryotic cell is the nucleoid. The nucleoid is the central part of the prokaryotic cell where the genetic material, DNA, is found.