This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
[{'content': 'Frequent blushing ("erethism") is associated with poisoning of \nSelect and explain. \nA. Mercury, B. Lead, C. Phenolic acid, D. Carbolic acid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mechanism of toxicity:Mercury reacts with sulfhydryl (SH) groups, resulting in enzyme inhibition and pathologic alteration of cellular membranes.Clinical presentation:Severe chemical pneumonitis and noncardiogenic pulmonary edema.Acute gingivostomatitis may also occur.Chronic intoxication:Classic triad Tremor Gingivostomatitis. Metallic tasteFrequent blushing ("erethism")Pain in the extremities, often accompanied by pinkish discoloration and desquamation ("pink disease")', 'role': 'assistant'}]