This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Molecular Genetics, Subject name: Biochemistry
[{'content': 'A nucleoside consists of: \nSelect and explain. \nA. Nitrogenous base, B. Purine or pyrimidine base + sugar, C. Purine or pyrimidine base + phosphorous, D. Purine + pyrimidine base + sugar + phosphorous', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Purine or pyrimidine base + sugarposition of nucleotides = Sugar + Base + Phosphate Composition of nucleosides = Sugar + Base. No phosphate is present.', 'role': 'assistant'}]