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: Anatomy
Most common primary bronchogenic carcinoma is 
Select and explain. 
A. Small cell carcinoma, B. Squamous cell carcinoma, C. Mixed cell carcinoma, D. Adenocarcinoma
D: Adenocarcinoma
Answer: D: Adenocarcinoma 
Explanation: Histological type . Frequency Adenocarcinoma . 32% Squamous cell carcinoma . 29% Small cell carcinoma . 18% Large cell carcinoma. 9% Carcinoid. 1% Ref Harrison 19th edition pg 2584