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: Biochemistry
[{'content': 'The predominant isozyme of LDH in cardiac muscle is: \nSelect and explain. \nA. LD-1, B. LD-2, C. LD-3, D. LD-5', 'role': 'user'}, {'content': "Answer: A \nExplanation: LD-1 is the predominant isoenzyme of LDH in cardiac muscle. Ref: Harper's Principles of Internal Medicine, 26th Edition, Page 57; Textbook of Biochemistry By Vasudevan, 5th Edition, Page 53", 'role': 'assistant'}]