This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of skin, Subject name: Dental
[{'content': 'Crystalline miliaria is due to obstruction to \nSelect and explain. \nA. Sweat gland, B. Sebaceous glands, C. Accessory sweat gland, D. Hair roots', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Miliaria crystallina is caused by obstruction of the sweat ducts close to the surface of the skin Miliaria rubra, caused by obstruction of the sweat ducts deeper in the epidermis; Miliaria profunda, the result of sweat leaking into the middle layer of skin (dermis). Ref Harrison20th edition pg 1207', 'role': 'assistant'}]