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
[{'content': 'In myocardium reperfusion injury is due to? \nSelect and explain. \nA. Ca, B. Mg, C. K, D. Mn', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Ca(Ref: Gross GJ, Kersten JR, Warltier DC. Mechanisms of postischemic contractile dysfunction. Ann Thorac Surg. 1999; 68:1898-1904.)Mediators of reperfusion injury are: Oxygen Free Radicals, Endothelial Dysfunction and Microvascular Injury, Alterations in Calcium Handling', 'role': 'assistant'}]