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 :

Question

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