This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
[{'content': 'Most common type cancer gallbladder in a patient with gallstones \nSelect and explain. \nA. Adenocarcinoma, B. squamous carcinoma, C. Adenosquamous carcinoma, D. Liposarcoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The most common cancer in a patient with gallstones is adenocarcinoma(90%).Occasionally squamous cell carcinoma,adenosquamous or carcinoid tumour can occur. Reference: SRB&;s manual of surgery,5th edition, page no.659', 'role': 'assistant'}]