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
Sign suggestive of carcinoma lung on chest X-ray is: 
Select and explain. 
A. Rib erosion, B. Central destruction within lesion, C. Flattening of diaphragm, D. Calcification
A: Rib erosion
Answer: A: Rib erosion 
Explanation: Ans. Rib erosion