This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Circulation: Cardiac Output, Venous Return, Subject name: Physiology
[{'content': 'Cardiac output is decreased by? \nSelect and explain. \nA. Increased Heart rate, B. Decreased Heart rate, C. Increased Stroke Volume, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: ANSWER: (B) Decreased Heart rateREF: Ganong's 22nd e p. 570-571Indirect repeat from June 2011Repeat(**)Cardiac output= Stroke volume X Heart rateCardiac output is decreased by decrease in either stroke volume or heart rate or both", 'role': 'assistant'}]