This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiration, Subject name: Pathology
A 45-year old male presented with severe respiratory distress. O/E he had pedal edema, bilateral crepitation on auscultation. He was admitted to emergency department and expired 2 days of admission. Lung biopsy done suggested the following. What is your diagnosis? 
Select and explain. 
A. CMV pneumonitis, B. Small cell Ca lung, C. Tuberculosis, D. Heart failure cells
D: Heart failure cells
Answer: D: Heart failure cells 
Explanation: Ans. (d) Heart failure cellsThe lung biopsy shows intra-alveolar transudate granular pale pink material along with alveolar micro-hemorrhages & hemosiderin-laden macrophages ("heart failure" cells) seen in left-sided congestive heart failure.