This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Enzymes, Subject name: Biochemistry
Which one of the following isoenzyme variants of Creatine kinase is elevated in myocardial infarction 
Select and explain. 
A. CK-BB, B. CK-MB, C. CK-MM, D. All the above
B: CK-MB
Answer: B: CK-MB 
Explanation: Tissue injury that results in damage to cell membranes and an increase in the permeability of the plasma membrane leads to leakage of intracellular material into the bloodstream (eg, leakage of Creatine kinase MB into the bloodstream following a myocardial infarction). Reference: Explanation: Harper's Biochemistry; 30th edition; Chapter 48; Clinical Biochemistry