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': 'Many dentists criticized the poor quality of the early amalgam restorations and this controversy led to the “amalgam war” from – \nSelect and explain. \nA. 1820  to  1830, B. 1840  to  1850, C. 1870  to  1880, D. 1880  to  1890', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Many dentists criticized the poor quality of the early amalgam restorations.This controversy led to the “amalgam war” from 1840 to 1850.\nReference: Phillip’s Science of Dental Materials, Pg-8', 'role': 'assistant'}]