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: Physiology
[{'content': 'Which of the following represents site of reversal of polarity of myosin molecules in thick muscle filaments? \nSelect and explain. \nA. M line, B. Z line, C. I line, D. H line', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The M line is the site of the reversal of polarity of the myosin molecules in each of the thick filaments. At these points, there are slender cross-connections that hold the thick filaments in proper array.', 'role': 'assistant'}]