A notochord is a:

A) spinal cord and a brain.
B) longitudinal flexible rod in the back.
C) segmented spine.
D) segmented spine and spinal cord.

Notochord

A flexible rod-shaped body found in the embryonic stage of all chordates that provides skeletal support.

Longitudinal

Pertaining to research or studies that follow the same subjects over a period of time to observe changes.

Flexible Rod

A structural element that is capable of bending or flexing under load while maintaining its integrity.