The correct answer is (a), bat. Bats are mammals, while birds are members of the class Aves. Birds are characterized by feathers, wings, a four-chambered heart, and a furcula (wishbone). Bats are characterized by wings formed by a membrane of skin stretched between elongated fingers and the body. They are also the only mammals that can fly.
(b) Crows are birds in the genus Corvus. They are highly intelligent and social birds, and are known for their ability to solve problems and their complex communication systems.
(c) Eagles are large, powerful birds of prey. They are found in many parts of the world, and are known for their keen eyesight and their ability to soar high in the sky.
(d) Parrots are colorful birds that are found in tropical and subtropical regions around the world. They are known for their intelligence and their ability to mimic human speech.