This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Radiology, Subject name: Radiology
Obscuration of left hea border is suggestive of 
Select and explain. 
A. Pneumothorax, B. Pleural effusion, C. Right upper lobe collapse, D. Lingular pathology
D: Lingular pathology
Answer: D: Lingular pathology 
Explanation: Silhouette sign : Obscuration of a mediastinal border occurs by a pathology which is in close anatomical contact with it Obscuration of Rt Hea Border Rt Middle Lobe Pathology Obscuration of Left Hea Border Lingular Pathology Obscuration Of Aoic Knuckle Left Apicoposterior pathology Obscuration of Hemidiaphgrams Lower lobe pathologies