A male newborn is delivered at term to a 30-year-old woman. Pregnancy and delivery were uncomplicated. At birth, the umbilical cord is noted to be large. When the newborn cries, straw-colored fluid leaks from the umbilicus. The external genitalia appear normal. Which of the following is the most likely cause of this newborn's symptoms? A Abnormal fusion of the urethral folds B Failed closure of the vitelline duct C Failed obliteration of an allantoic remnant D Infection of the umbilical cord stump E Incomplete closure of the lateral folds F Malformation of the medial umbilical ligament