The correct answer is: B. Craniata
Craniata is a subphylum of chordates that includes all animals with a skull. This includes vertebrates, as well as some invertebrate chordates such as lancelets.
Pisces is a class of vertebrates that includes fish. Fish are aquatic animals that have gills, fins, and scales.
Aves is a class of vertebrates that includes birds. Birds are warm-blooded, feathered animals that can fly.
Amphibia is a class of vertebrates that includes frogs, toads, salamanders, and caecilians. Amphibians are ectotherms, meaning that their body temperature changes with the temperature of their environment. They have smooth, moist skin and lay eggs in water.
Craniata is the correct answer because it is the only option that includes all vertebrates. Pisces, Aves, and Amphibia are all classes of vertebrates, but they do not include all vertebrates.