Out of ‘X’ pairs of ribs in humans, generally ‘Y’ pairs are floating ribs. Select the option that correctly represents values of ‘X’ and ‘Y’ and explains why they are called floating ribs.

• A

  X=12; Y=2 -  They are dorsally not attached to the vertebral column

• B

  X=24; Y=4 - They are ventrally free

• C

  X=12; Y=2 - They are ventrally not connected to the sternum or other ribs

• D

  X=24; Y=6 - Their costal cartilages join the 7th rib