This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abdomen & Pelvis, Subject name: Anatomy
Fusion of the caudal portions of the kidneys during embryonic development is most likely to result in which of the following congenital conditions? 
Select and explain. 
A. Bicornuate uterus, B. Cryptorchidism, C. Horseshoe kidney, D. Hypospadias
C: Horseshoe kidney
Answer: C: Horseshoe kidney 
Explanation: During development, the kidneys typically "ascend" from a position in the pelvis to a position high on the posterior abdominal wall. Although the kidneys are bilateral structures, occasionally the inferior poles of the two kidneys fuse. When this happens, the "ascent" of the fused kidneys is arrested by the first midline structure they encounter, the inferior mesenteric artery. The incidence of horseshoe kidney is about 0.25% of the population.