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: Pharmacology
[{'content': 'True statement(s) out of the following is/are: a) β1  receptors in heart stimulate its contractions b) β2 receptors in heart stimulate its contractions c) β2 receptors are present in smooth muscles d) α1 receptors cause preganglionic stimulation e) α2  receptors cause postganglionic feedback inhibition \nSelect and explain. \nA. ac, B. ad, C. bc, D. b', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]