This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
Which cation is found in extremely high concentrations in cells that have undergone coagulative necrosis? 
Select and explain. 
A. Potassium, B. Calcium, C. Iron, D. Cobalt
B: Calcium
Answer: B: Calcium 
Explanation: Coagulative necrosis is characterized by a massive influx of calcium into the cell. Under normal circumstances the plasma membrane maintains a steep gradient of calcium ions, whose concentration in interstitial fluids is 10,000 times higher than that inside the cell. Irreversible cell injury damages the plasma membrane, which then fails to maintain this gradient, thereby allowing the influx of calcium into the cell.