This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Oncology, Subject name: Medicine
[{'content': 'Commonest type of bronchogenic carcinoma is - \nSelect and explain. \nA. Adenocarcinoma, B. Oat cell carcinoma, C. Squamous cell carcinoma, D. Large cell carcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Adenocarcinoma: The neoplasm is composed of malignant glandular epithelium which may vary in degree of differentiation from tumor to tumor. Well differentiated neoplasms may form distinct glands, other neoplasms may vary from forming papillary structures to solid neoplasms without any gland formation. Adenocarcinomas tend to be smaller than other bronchogenic carcinomas and located in the periphery of the lung. A distinctive type of adenocarcinoma is bronchioloalveolar carcinoma Ref Harrison 20th edition pg 590', 'role': 'assistant'}]