This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cellular Pathology, Subject name: Pathology
A 33-year-old woman has had increasing lethargy and decreased urine output for the past week. Laboratory studies show her serum creatinine is 4.3 mg/ dL and urea nitrogen 40 mg/dL. A renal biopsy is performed, and the specimen is examined using electron microscopy. Which of the following morphologic cellular changes most likely suggests a diagnosis of acute tubular necrosis? 
Select and explain. 
A. Chromatin clumping, B. Mitochondrial swelling, C. Nuclear fragmentation, D. Plasma membrane blebs
C: Nuclear fragmentation
Answer: C: Nuclear fragmentation 
Explanation: Cell death occurs with loss of the cell nucleus, and tubular cells become necrotic. All other cellular morphologic changes listed represent forms of reversible cellular injury. The plasma membrane and intracellular organelles retain some function unless severe damage causes loss of membrane integrity.