The Correct Answer is Birds.

• 'Ornithology' is a branch of zoology that concerns the Methodological study and consequent knowledge of birds with all that relates to them.
• Several aspects of 'Ornithology' differ from related disciplines, due partly to the high visibility and the aesthetic appeal of birds.
• The word 'Ornithology' comes from the late 16th-century Latin Ornithologia meaning 'bird science' from the Greek.

• Mammals are a group of vertebrate animals constituting the class Mammalia and characterized by the presence of mammary glands which in females produce milk for feeding their young, a neocortex, fur or hair and three middle ear bones.
• Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. They form a sister group to the tunicates, together forming the olfactores. The earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period.
• Bats are mammals of the order Chiroptera. With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight.