Answer:
The Best Definition of a Prokaryote is "A one-celled organism that does not have a cell membrane-bound nucleus."
What Is a Prokaryote?
The best definition of a prokaryote is an organism that lacks a distinct nucleus and other organelles due to the absence of internal membranes. Bacteria are among the best-known prokaryotic organisms. The lack of internal membranes in prokaryotes distinguishes them from eukaryotes.
So, out of the options you provided, the closest definition would be “A one-celled organism that does not have a cell membrane-bound nucleus”.