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: Pathology
[{'content': 'Which of the following is an example of a directly acting toxin? \nSelect and explain. \nA. Acetaminophen, B. Mercuric chloride, C. Carbon tetrachloride, D. Bromobenzene', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Directly acting toxins:\nSome toxins act directly by combining with a critical molecular component or cellular organelle. For example, in mercuric chloride poisoning,\xa0mercury binds to the sulfhydryl groups of various cell membrane proteins, causing inhibition of ATP-dependent transport and increased membrane permeability.', 'role': 'assistant'}]