This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': "Watson's DNA model is : \nSelect and explain. \nA. Right handed, parallel, B. Left handed, anti parallel, C. Left handed, parallel, D. Right handed, anti parallel", 'role': 'user'}, {'content': 'Answer: D \nExplanation: Chemically, DNA consists of two long polymers of simple units called nucleotides, with backbones made of sugars and phosphate groups joined by ester bonds.This common form of DNA is said to be right handed because as one looks down the double helix, the base residues form a spiral in a clockwise direction.These two strands run in opposite directions to each other and are therefore anti-parallel.', 'role': 'assistant'}]