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
Which of the following congenital malformations will most predictably result in oligohydramnios? 
Select and explain. 
A. Anencephaly, B. Pyloric stenosis, C. Renal agenesis, D. Tracheoesophageal fistula
C: Renal agenesis
Answer: C: Renal agenesis 
Explanation: In normal kidney development the kidneys function during the fetal period with the resulting urine contributing to the fluid in the amniotic cavity. When the kidneys fail to develop (renal agenesis), this contribution to the fluid is missing and decreased amniotic fluid (oligohydramnios) results.