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': 'Vagal stimulation of the hea causes all, EXCEPT: \nSelect and explain. \nA. Decreased Hea Rate, B. Decreased force of Hea contraction, C. Decreased Cardiac Output., D. Decreased R-R interval in ECG', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Parasympathetic supply to the hea by vagus nerve causes decreased hea rate, decreased force of contraction, decreased cardiac output. R-R interval is the time interval between consecutive hea beats in the ECG. So a decrease in hea rate increases the R-R interval.', 'role': 'assistant'}]