This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
[{'content': 'Which of the following is the only reversible cataract: \nSelect and explain. \nA. Senile cataract, B. Cataract in galactosemia, C. Congenital cataract, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Cataract in galactosemia', 'role': 'assistant'}]