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: Surgery
[{'content': 'The commonest site of lodgement of a pulmonary embolus is in the territory of - \nSelect and explain. \nA. Rt. lower lobe, B. Rt. upper lobe, C. Lt. lower lobe, D. Lt. upper lobe', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Lt. upper lobe", 'role': 'assistant'}]