Describe the diversity of the animal kingdom

In the animal kingdom there is a lot of diversity...

First:
There are carnivores, herbivores and omnivores. Carnivores eat strictly meat. Herbivores eat vegetation and plants. Omnivores are like you and I, we eat anything, meat, vegetation, etc. 

Second: 
There are several main classes, the Land Animals, the Sea Animals and the Air Animals. 
Land: Anything such as horses, deer, cats, camels, lizards, bears, foxes, moles, mice, dogs, tigers, lions, zebra, cows, goats, pigs, ocelots, monkeys, etc. 
Sea: Sharks, fish, octopus, dolphins, whales, sea horses, sea urchins, eels, sturgeon, angel fish, etc. 
Air: Hawks, eagles, vultures, toucans, parrots, crows, ravens, blackbirds, blue jays, chickadees, woodpeckers, swallows, etc. 

Third: 
There are classes such as feathered (birds), scaled (reptiles), furred and such.
Feathered: Chickens, eagles, toucans, turkeys, grouse, ravens, crows, etc.
Scaled: Lizards, snakes, sharks, fish, etc.
Furred: (Domestic) Horses, cows, dogs, cats, monkeys, etc. (Non domestic) Lions, tigers, bears, deer, elk, moose, etc. 

The right answer is b hydrogen bonds!