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': 'You are examining a postoperative patient who believed to have lost 20% of his blood. What change if any would you expect in his BP and hea rate? \nSelect and explain. \nA. Hea rate increased, BP reduced, B. Hea rate increased, BP normal/unchanged, C. Hea rate normal/unchanged, BP reduced, D. Hea rate unchanged, BP unchanged', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The change in BP and pulse rate in relation to % of blood loss is given below: Blood loss BP Hea rate <15% no change slight increase 15 - 30 % no change 100 - 120 30 - 40 % reduced >120, weak pulse >40% markedly reduced > 120, thready pulse Ref: Bailey, Edition 23, Page 235', 'role': 'assistant'}]