This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
[{'content': 'Primary oocyte is formed after \nSelect and explain. \nA. First meiotic division, B. Second meiotic division, C. Mitotic division, D. None of the above', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In the female, the primordial germ cells (oogonia) continue to proliferate by mitosis, reaching a peak of 5-7 million by 20 weeks of gestation. However, only some enter meiosis and become primary oocytes, arresting in diplotene of the first meiotic prophase, and become surrounded by a single layer of flattened pregranulosa cells, forming primordial follicles.Ref: Clinical endocrinology and infeility; 8th edition; Chapter 3; The Ovary--Embryology and Development', 'role': 'assistant'}]