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': 'Sign of inoperability of ovarian tumour is : \nSelect and explain. \nA. Excrescences over surface, B. Stromel invasion, C. Peritoneal involvement, D. Pelvic metastasis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Peritoneal involvement', 'role': 'assistant'}]