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 increased risk of pyelonephritis is in pregnancy is due to which of the following factors \nSelect and explain. \nA. Statis of urine, B. Asymptomatic bacteriuria, C. Abnormality in renal tract, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans: D', 'role': 'assistant'}]