Select the option that can be used as a one-word substitute for the given group of words.
An animal that can live in water as well as on land

* Amphibian is a cold-blooded vertebrate animal of a class that comprises frogs, toads, newts, and salamanders, distinguished by having an aquatic gill-breathing larval stage followed by a terrestrial lung-breathing adult stage.
Carnivore is an animal that feeds on flesh.

Mammal is a warm-blooded vertebrate animal distinguished by the possession of hair or fur, secretion of milk, and the birth of live young.

Herbivore is an animal that feeds on plants.