This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pediatrics
Which of the following is the most common renal cystic disease in infants is ? 
Select and explain. 
A. Polycystic kidney, B. Simple renal cyst, C. Unilateral renal dysplasia, D. Calyceal cyst
C: Unilateral renal dysplasia
Answer: C: Unilateral renal dysplasia 
Explanation: Unilateral renal dysplasia is a form of renal dysplasia (RD; see this term), a renal tract malformation in which the development of one kidney is abnormal and incomplete. Unilateral RD can be segmental, and of variable severity, with renal aplasia corresponding to extreme RD. Reference: GHAI Essential pediatrics, 8th edition