A newborn baby has a prominent defect at the base of his spine through which his meninges and spinal cord protrude. A failure of which of the following processes is the most common cause of this type of defect?: (A) Development of primary veebral ossification centers, (B) Development of the pedicle, (C) Development of the superior aicular process, (D) Fusion of the veebral arches
Answer is D. .