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': 'In a case of carcinoma cervix involvement of parametrium, lower 1/3 of vagina and no free space on P/R examination means stage : \nSelect and explain. \nA. Ila, B. Ilb, C. Illa, D. Illb', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ilb', 'role': 'assistant'}]