Circular DNA occurs inA. Bacteria onlyB. Bacteria and ChloroplastsC. All virusD. Bacteria, Chloroplasts and Mitochondria

The correct answer is D. Bacteria, Chloroplasts, and Mitochondria
Circular DNA is found in several organisms, particularly in prokaryotes and certain organelles within eukaryotic cells. Here’s a detailed explanation for each option:
• A. Bacteria only: While bacteria do have circular DNA (in the form of a single circular chromosome), this answer is incomplete because circular DNA is also found in other organisms (like mitochondria and chloroplasts).
• B. Bacteria and Chloroplasts: This is partially correct because bacteria and chloroplasts do have circular DNA, but it misses the presence of circular DNA in mitochondria.
• C. All viruses: This is incorrect because not all viruses have circular DNA. Some viruses have linear DNA or RNA as their genetic material.
• D. Bacteria, Chloroplasts, and Mitochondria: This is the correct answer.
o Bacteria have a single, circular DNA chromosome.
o Chloroplasts (found in plant cells) and mitochondria (found in animal and plant cells) also contain their own circular DNA. These organelles are thought to have evolved from ancient symbiotic bacteria and retain circular DNA similar to bacterial chromosomes.
Circular DNA occurs in bacteria, chloroplasts, and mitochondria, making (D) the correct answer.