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': 'A 17 year old girl with acne has been taking a drug for the last two years.She now presents with blue black pigmentation of nails.The likely medication causing above pigmentation is- \nSelect and explain. \nA. Tetracycline, B. Minocyclin, C. Doxycycline, D. Azithromycin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mincycline induced pigmentation in acne- due to accumulation of iron in dermal macrophages occur with prolonged therapy 1-3 years high dose 200-300mg/day three different patterns - Localised at sites of previous inflammation -acne scars pretibial area generalised over the sun exposed sites and nails Ref Harrison 20th edition pg 1213', 'role': 'assistant'}]