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: Dental
[{'content': 'The connective tissue cells of pulp are derived from \nSelect and explain. \nA. The pool of undifferentiated mesenchymal cells, B. The pool of fibroblasts, C. The pool of undifferentiated ectodermal cells, D. The pool of osteoblasts', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]