Final answer:
The organelle unique to prokaryotes and comprised of supercoiled DNA is the nucleoid. Hence the correct answer is option C
Step-by-step explanation:
The organelle that is unique to prokaryotes and comprised of supercoiled DNA is the nucleoid. Prokaryotic cells, such as bacteria and cyanobacteria, do not have a nucleus like eukaryotic cells. Instead, their DNA is located in the nucleoid region of the cell. The nucleoid is not surrounded by a membrane, and the DNA is tightly coiled to form a supercoiled structure.
Hence the correct answer is option C