Question

Fish are classified as vertebrates because they have

a. a brain.
b. a backbone.
c. two germ layers.
d. bilateral symmetry.

Answer 1

the answer is b) a backbone

Answer 2

B, a backbone.

Not A, because we know some species that aren't vertebrates and have a brain.
C. two germ layers, isn't a characteristic specific to vertebrates.
d. bilateral symmetry, no for the same reasons as A.