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 toxic form of mercury is \nSelect and explain. \nA. Methyl and ethyl mercury, B. Mercury vapour, C. Inorganic mercury forms, D. Mercury sulphide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]