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': 'Yoyo reflux \nSelect and explain. \nA. Duplication of ureter, B. Polycystic Kidney, C. Mellutary sponge Kidney, D. Pseudo kidney', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer- A. Duplication of ureterReflux of the urine from one limb of the collecting system to the other limb, rather than down towards the bladder is called yo-yo reflux (saddle reflux)Cause : Duplication of ureters, paial duplication ofureters, duplicate renal pelvis', 'role': 'assistant'}]