This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Commonest carcinoma in men in tropical countries - \nSelect and explain. \nA. Ca rectum, B. Ca oral cavity, C. Ca testis, D. Ca bladder', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Oral cancer is one of the ten most common cancers in the world Mostly due to Tobacco Alcohol Precancerous state Cultural pattern Ref- Park&;s textbook of Preventive and Social Medicine 24th edition.', 'role': 'assistant'}]