This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Skin
[{'content': 'Hyperkeratosis is: \nSelect and explain. \nA. Thinning of Stratum corneum, B. Thickening of stratum corneum, C. Thinning of stratum basale, D. Thickening of stratum basale', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Thickening of stratum corneumRef: Fitzpatrick 7th ed. / 384', 'role': 'assistant'}]