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: Radiology
All are seen in left atrium enlargement except: 
Select and explain. 
A. Posterior displacement of the oesophagus on barium meal, B. Straightening of the left main hronchus, C. A double shadow of right atrium, D. Retrosternal lucency on lateral film
D: Retrosternal lucency on lateral film
Answer: D: Retrosternal lucency on lateral film 
Explanation: Ans. Retrosternal lucency on lateral film