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

Options

A. X=12, Y=7 True ribs are attached doresally to vertebral column and ventrally on the sternum.
B. X=12, Y=5 True ribs are attached dorsally to vertebral column and sternum on the two ends.
C. X=24, Y=7 True ribs are dorsally attached to vertebral column but are free on ventral side.
D. X=24, Y=12 True ribs are dorsally attached to vertebral column, but are free on ventral side.

Answer

A

Explanation

In the rib cage, the ture ribs are those which are attached to the sternum in the fron and vertebral column at back. These are 7 in numbers. Although there are total 12 ribs in the rib cage. The 11th and 12th ribs are attached to the vertebral column and keep floating in the thoracic cavity, so are called floating ribs.