A boy is examined in the newborn nursery shortly after birth. He was born full term by vaginal delivery to a 40-year-old woman who did not receive prenatal care. His temperature is 36.7 C (98 F), pulse is 132/min, and respirations are 38/min. Examination shows slanted palpebral fissures, epicanthal folds, thick nuchal folds, and a single palmar crease. The patient has a large, reducible midline abdominal protrusion covered by skin that is more pronounced when he cries. The umbilical stump is at the center of the protrusion. Which of the following is the most likely cause of this patient's abdominal finding?
1) Failure of the extraembryonic gut to return to the abdominal cavity
2) Incomplete closure of the umbilical ring
3) Incomplete recanalization of the fetal intestinal tract
4) Incomplete rotation of the midgut in utero
5) Persistent processus vaginalis