This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'Mitochondria have \nSelect and explain. \nA. Plasmid DNA, B. Circular DNA, C. Single stranded DNA, D. Double stranded circular DNA', 'role': 'user'}, {'content': "Answer: D \nExplanation: human mitochondrial DNA is a double-stranded circular molecule containing approximately 16,500 base pairs.(REF: GANONG'S REVIEW OF MEDICAL PHYSIOLOGY 23rd EDITION page no.34.)", 'role': 'assistant'}]