This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'A 45-year-old man has recently been the recipient of a hea transplant. Which one of the following drug is least likely to cause tachycardia in this patient \nSelect and explain. \nA. Amphetamine, B. Dobutamine, C. Epinephrine, D. Norepinephrine', 'role': 'user'}, {'content': "Answer: A \nExplanation: The transplanted hea doesn't have sympathetic innervation. Hence an indirectly acting sympathomimetic like Amphetamine has the least likelihood of causing tachycardia when compared to the directly acting ones.", 'role': 'assistant'}]