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': 'Most common ovarian tumour to undergo torsion: \nSelect and explain. \nA. Pseudomucinous cystadenoma, B. Papillary cystadenoma, C. Dermoid cyst, D. Mucinous cyst', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Dermoid cyst', 'role': 'assistant'}]