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: Anatomy
[{'content': 'All of the following structures undergo mass contraction except \nSelect and explain. \nA. Ureter, B. Uterus, C. Urinary bladder, D. Gall bladder', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Urine production by the kidneys is a continuous process. The contraction of the ureter is peristalic and not mass contraction. All other options are organs which show mass contraction.', 'role': 'assistant'}]