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': 'Cystocele is formed by of the bladder : \nSelect and explain. \nA. Base, B. Superior surface, C. Trigone, D. Posterior', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Base', 'role': 'assistant'}]