Correct Answer - D
Usually, there are 12 pairs of ribs, but occasionally these may be 11, 13 or even 14 pairs. The first seven pairs of ribs are known as true ribs.
Pairs 8, 9, 10 are false ribs they are attached indirectly to stemum by means of cartilages. Last two pairs (11 and 12) do not reach to the stemum and are known as floating ribs.
