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': 'Protein responsible for preventing overstretching of cardiac muscle \nSelect and explain. \nA. Actinin, B. Nebulin, C. Myomesin, D. Titin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Titin is responsible for elasticity of muscle and preventing overstretching of cardiac muscle.', 'role': 'assistant'}]