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: Surgery
[{'content': 'Which is a normal finding in cystometry \nSelect and explain. \nA. Absence of systolic detrussor contraction, B. Residual volume of 75 ml, C. Leakage on coughing, D. First sensation of urination at 300 ml', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]