This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Congenital malformations, Subject name: Gynaecology & Obstetrics
[{'content': 'Vaginal epithelium is derived from \nSelect and explain. \nA. Endoderm of urogential sinus, B. Mesoderm of urogential sinus, C. Endoderm of gential ridge, D. Mesoderm of gential ridge', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Vaginal epithelium is derived from the endoderm of the urogenital sinus Sinovaginal bulbs fuse to form vaginal plate which breaks down in centre to form lumen of vagina Peripheral cells of vaginal plate forms the vaginal epithelium Hymen is formed by invagination of the posterior wall of the urogenital sinus Ref: Essentials of embryology and bih defects; Ninth edition; chapter 13', 'role': 'assistant'}]