Primary vertebral curve is -

Ans. is 'a' i.e., Thoracic o During fetal life and at birth the vertebral column shows a continuous curvature with the concavity direct forwardso In fully developed spine, thoracic and sacral curvatures are (concave forwards' and hence are called primary curvatures. Cervical and lumbar curves are convex forwards (or concavity backwards) and are termed as "secondary curvatures' because they develop after birth.o Cervical curvature develops 3-4 months after birth and lumbar curvature develops 12-15 months after birth.