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': 'A shift of posture from supine to upright posture is associated with cardiovascular adjustments. Which is not true in this context \nSelect and explain. \nA. Rise in central venous pressure, B. Rise in HR, C. Decrease in cardiac output, D. Decrease in stroke volume', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]