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: Gynaecology & Obstetrics
[{'content': 'Maximum number of oogonia is seen at \nSelect and explain. \nA. Puberty, B. 20th week of gestation, C. At birth, D. 20 years age', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Maximal number of oogonia is achieved at 20th week of gestation.', 'role': 'assistant'}]