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: Medicine
[{'content': 'In cardiac shock - \nSelect and explain. \nA. SBP < 90 mm of Hg, B. DBP < 80 mm of Hg, C. Cardiac index <3.5, D. Stroke volume 70 ml', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]