Which one of the following item gives its correct total number?

Step-by-step solution

There are 12 pairs of ribs in human, which form the bony lateral walls of the thoracic cage. The last two pair of ribs (total four) are called floating ribs because their anterior ends are not attached to either the sternum or the cartilage of another rib. The floating ribs protect the kidneys. There are 7 cervical vertebrae in humans present in neck. The first cervical vertebra is called atlas and second is known as axis. There are 20 amino acids found in proteins.