Which of the following correctly matches each vertebrate to its classification?

A.
bird → Y
fish → W
mammal → Z
reptile → X

B.
bird → Z
fish → Y
mammal → W
reptile → X

C.
bird → X
fish → Z
mammal → W
reptile → Y

D.
bird → W
fish → X
mammal → Y
reptile → Z

B. bird → Z, fish → Y, mammal → W, reptile → X