Answer: Option A
:
A
Sub-phylum Vertebrata is classified into two divisions based on the presence or absence of jaws - Agnatha and Gnathostomata. The former includes the jawless vertebrates while the latter includes the jawed forms. Division Agnatha includes just one class - Cyclostomata. Examples of this jawless class are lamprey and hagfish. Fishes are jawed, and are grouped under division Gnathostomata. Jellyfish is an invertebrate that is classified under Phylum Cnidaria.