This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skin lesions and disorders of pigmentation, Subject name: Dental
[{'content': 'Rain drop pigmentation is seen in \nSelect and explain. \nA. Chronic lead poisoning, B. Chronic Arsenic poisoning, C. Chronic Mercury poisoning, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: chronic arsenic exposure from occupations for polonged periods 1-20 years may develop diffuse pigmentation predominant over trunk and is superimposed by 2-10mm macules of depigmentation producing characteristic rain drop appearence. IADVL textbook of dermatology, disorders of pigmentation page 786', 'role': 'assistant'}]