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': 'In erect posture commonest site of foreign body in bronchus - \nSelect and explain. \nA. Right posterior basal, B. Right anterior basal, C. Lateral basal, D. Medial basal', 'role': 'user'}, {'content': 'Answer: A \nExplanation: From Schwart, 7/e→ "The most common anatomic location for a foreign body is the right main stem bronchus or the rt. lower lobe."\nFrom Pretest (Pretest has quoted Harrison, 14/e, p 994)\n" The right main stem bronchus is wider, shorter and vertically placed, and therefore the posterior segments of the right upper lobe (if the pt. aspirated while supine) are anatomically susceptible to aspiration pneumonia. The superior segments of the right lower lobe and left lower lobe (if the pt. supine) are also susceptible to aspiration pneumonia. These three segments are often referred to as the aspiration segments of the lung. The basilar segments of both lungs are susceptible to aspiration if the pts. aspirates while erect or sitting up."\n\n\nInference : Segments involved\n\nAspiration in Supine Position :\n\nRL upper lobe - posterior segment\nRt. lower lobe - superior segment\nLt. lower lobe - superior segment\n\nAspiration in sitting or erection position\n\nRt. basilar segments (of lower lobe).', 'role': 'assistant'}]