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: Anatomy
[{'content': 'Which of the following does not form the ground substance \nSelect and explain. \nA. Glycosaminoglycans, B. Collagen fibers, C. Proteoglycans, D. Multiadhesive glycoproteins', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]