Which Statement Best Describes a Myelomeningocele

Which statement best describes a myelomeningocele?

A) Fissure in the spinal column that leaves the meninges and the spinal cord exposed.
B) Herniation of the brain and meninges through a defect in the skull.
C) Hernial protrusion of a sac-like cyst of meninges with spinal fluid but no neural elements.
D) Visible defect with an external sac-like protrusion containing meninges, spinal fluid, and nerves.