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
A most common site for squamous cell ca. esophagus is 
Select and explain. 
A. Upper third, B. Middle third, C. Lower third, D. Gastro-esophageal junction.
B: Middle third
Answer: B: Middle third 
Explanation: Distribution of Squamous cell Ca

Upper 1/3 - 10%
Middle 1/3 - 60%         
Lower 1/3 - 30%