Correct option is A. a - fishes, b - mammals, c - birds, d reptiles, e amphibians
A) Fishes have the highest diversity among the vertebrates.
B) Birds constitute the second highest group after the fishes.
C) Reptiles rank third among the vertebrates in terms of diversity.
D) Amphibians come on the second last position.
E) Mammals comprise the last position in the extent of global diversity.
So, the correct answer is 'a - fishes, b - mammals, c - birds, d reptiles, e amphibians'.