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: Anatomy
[{'content': 'Vaginal sphincter is formed by all except - \nSelect and explain. \nA. Internal urethral sphincter, B. External urethral sphincter, C. Pubovaginalis, D. Bulbospongiosus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Urogenital sphincters in Females\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0Vaginal sphincters\n\nBulbospongiosus\nSphincter urethrovaginalis\nExternal urethral sphincter\nPubovaginalis\n\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0\xa0Urinary sphincters\n\nCompressor urethrae\nExternal urethral sphincter\nSphincter urethrovaginalis\nPubourethralis', 'role': 'assistant'}]