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 most important disadvantage of acrylic denture base is \nSelect and explain. \nA. Porosity, B. Shrinkage, C. Tooth breakage, D. Water absorption', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]