This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrine System, Subject name: Physiology
[{'content': 'Following is/are physiological effects of thyroid hormones on the hea: \nSelect and explain. \nA. Increased number of beta adrenergic receptors, B. Blunted response to circulating catecholamines, C. Increased propoion of beta myosin heavy chain, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]