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: Pathology
Which of the following is the characteristic of irreversible injury on electron microscopy? 
Select and explain. 
A. Disruption of ribosomes, B. Amorphous densities in mitochondria, C. Swelling of Endoplasmic reticulum, D. Cell swelling
B: Amorphous densities in mitochondria
Answer: B: Amorphous densities in mitochondria 
Explanation: One of the characteristic features of irreversible injury on electron microscopy is marked dilation of mitochondria with the appearance of large amorphous densities.