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
All of the following structures undergo mass contraction except 
Select and explain. 
A. Ureter, B. Uterus, C. Urinary bladder, D. Gall bladder
A: Ureter
Answer: A: Ureter 
Explanation: 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.