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: Anatomy
[{'content': 'Commonest type of carcinoma with gallstones is \nSelect and explain. \nA. Adenocarcinoma, B. Anaplastic carcinoma, C. Squamous cell carcinoma, D. Transitional cell carcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Histological types of gallbladder carcinoma Diffuse infiltrative : MC type Nodular or mass forming Papillary : Exhibits polypoid or cauliflower appearance and have best prognosis Adenocarcinoma : MC histological subtype of CA GB associated with gallstones Ref: Sabiston 20th edition Pgno : 1512-1514', 'role': 'assistant'}]