The correct option is C Procoelous
Vertebrae of frogs
Vertebrae are bones located within the vertebral column.
The frogs possess 10 vertebrae and among them, the 2nd to 7th vertebrae are named as typical vertebrae.
The vertebrae consist of a centrum (or body), 1 or 2 arches and other parts.
Procoelous
In the procoelous vertebrae, the centrum is concave in front & convex in back.
It is present in most reptiles and also in amphibians like frogs.