Select the amphibian.

 - domestic pig
 - western rattlesnake
 - green tree frog
 - water buffalo
A domestic pig is a mammal. It has hair and feeds its young milk.
Pigs are omnivores. This means that they can eat both plants and animals.
A western rattlesnake is a reptile. It has scaly, waterproof skin.
Rattlesnakes have fangs they can use to inject venom into their prey.
A water buffalo is a mammal. It has hair and feeds its young milk.
Water buffaloes live in Asia. Some people raise water buffaloes for their milk.
A green tree frog is an amphibian. It has moist skin and begins its life in water.
There are many kinds of tree frogs. Most tree frogs are very small. They can walk on thin branches.