This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Pathology
True about lung carcinoma - 
Select and explain. 
A. More than 75% of lung cancers are squamous cell type, B. Oat cell carcinoma frquently show cavitation, C. Lung calcification is characteristically seen in oat cell carcinoma, D. Oat cell carcinoma is commonly associated with bilateral hilar lymphadenopathy
D: Oat cell carcinoma is commonly associated with bilateral hilar lymphadenopathy
Answer: D: Oat cell carcinoma is commonly associated with bilateral hilar lymphadenopathy 
Explanation: Ref:Textbook of pathology (Harsh mohan) 6th edition,page no.500 Oat cell carcinoma is composed of uniform, small cells, larger than lymphocytes with dense, round or oval nuclei having diffuse chromatin, inconspicuous nucleoli and very sparse cytoplasm (oat = a form of grain). These cells are organised into cords, aggregates and ribbons or around small blood vessels forming pseudorosettes.Theyare commonly associated with bilateral hilar lymphadenopathy.