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': 'The critical mitogen for uterine fibroid growth is \nSelect and explain. \nA. Estrogen, B. Progesterone, C. IGF - I & II, D. Corticosterone', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cell proliferation, extracellular matrix accumulation and cell hypertrophy which all lead to leiomyoma growth are controlled by progesterone directly.', 'role': 'assistant'}]