The number of lumbar vertebrae in the human vertebral column is

Which ribs are attached to the sternum?

Out of $X$ pairs of ribs in humans,only $Y$ pairs are true ribs. Select the option that correctly represents the values of $X$ and $Y$ and provides their explanation.

How many pairs of ribs are present in human beings (in $pairs$)?

Nucleus pulposus is

Floating ribs of the thoracic cage are