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: Unknown
[{'content': 'The pressure used in pneumatic tourniquet in upper limb is upto: \nSelect and explain. \nA. Systolic Blood Pressure + 50, B. Systolic Blood Pressure + 75, C. Systolic Blood Pressure + 100, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Pneumatic tourniquet is a narrow rubber bag to be wound around a limb, pressure being applied by pumping air into the inflatable cuff.\nA bloodless field is obtained by applying pressure through pneumatic tourniquet for accurate surgery. Usually pressure applied 75 mmHg over systolic blood pressure for not more than 2 hours.', 'role': 'assistant'}]