Cyclostomata, like lamprey eels and hagfish,

Cyclostomata, like lamprey eels and hagfish, have cartilage skeletons. The correct option among all the options that are given in the question is option "b". Lamprey eels and hagfish do not have any bones in their body. Hagfish are either predators or scavengers. On the other hand, Lampreys that feed on detitrus as well as scavenge.

The most common basis for grouping organisms is: The Structure