This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Mitochondrial DNA is \nSelect and explain. \nA. Closed circular, B. Nicked circular, C. Linear, D. Open circular', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that conve chemical energy from food into a form that cells can use, adenosine triphosphate (ATP). Ref-Harpers illustrated biochemistry 30/e p585', 'role': 'assistant'}]