Explanation:
The ribs are a set of twelve bones which form the protective 'cage' of the thorax. They articulate with the vertebral column posteriorly, and terminate anteriorly as cartilage (known as costal cartilage). As part of the bony thorax, the ribs protect the internal thoracic organs.
The answer would be : a. angiosperms.
Source : https://en.wikipedia.org/wiki/Flowering_plant
Hope this helps !
Photon
