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
Loss of cardiac silhoutee is seen in pathology of: 
Select and explain. 
A. Rt. Middle lobe, B. Rt. Lower lobe, C. Rt. Atria, D. Rt. Ventricle
A: Rt. Middle lobe
Answer: A: Rt. Middle lobe 
Explanation: Ans. Rt. Middle lobe