This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
Most pathognomic sign of irreversible cell injury 
Select and explain. 
A. Amorphous densities in mitochondria, B. Swelling of the cell membrane, C. Ribosomes detached from endoplasmic reticulum, D. Clumping of nuclear chromatin
A: Amorphous densities in mitochondria
Answer: A: Amorphous densities in mitochondria 
Explanation: Ref Robbins 9/e p50 Mitochondrial Damage and Dysfunction Mitochondria may be viewed as "mini-factories" that produce life-sustaining energy in the form of ATP. Not surprisingly, therefore, they are also critical players in cell injury and death (Fig. 1-16). Mitochondria are sensitive to many types of injurious stimuli, including hypoxia, chemi- cal toxins, and radiation. Mitochondrial damage may result in several biochemical abnormalities: * Failure of oxidative phosphorylation leads to progres- sive depletion of ATP, culminating in necrosis of the cell, as described earlier. * Abnormal oxidative phosphorylation also leads to the formation of reactive oxygen species, which have many deleterious effects, described below. * Damage to mitochondria is often associated with the formation of a high-conductance channel in the mito- chondrial membrane, called the mitochondrial permea- bility transition pore. The opening of this channel leads to the loss of mitochondrial membrane potentialand pH changes, fuher compromising oxidative phosphorylation. * The mitochondria also contain several proteins that, when released into the cytoplasm, tell the cell there is internal injury and activate a pathway of apoptosis, dis- cussed later.