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: Skin
[{'content': 'Which is a specific lesion of acne vulgaris? \nSelect and explain. \nA. Papules, B. Pustules, C. Comedones, D. Wheals', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. c. ComedonesComedones are pathognomonic of acne.Comedones are the keratin plugs of the pilosebaceous ducts.When the keratin plug is inside the follicle, it is called closed comedone (whitehead).When the keratin plug is exposed to the environment, it turns black and is known as open comedone (blackhead).Comedonal lesions are the earliest lesions of acne.', 'role': 'assistant'}]