This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Anatomy
[{'content': 'Blood loss during major surgery is best estimated by \nSelect and explain. \nA. Visual assessment, B. Suction bottles, C. Cardiac output, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Blood loss during operation is measured by - Weighing the swabs after use and subtracting the dry weight + Volume of blood collected in suction or drainage This is k/a Gravimetric method of estimation of blood loss', 'role': 'assistant'}]