Bill the explorer was hiking through the Brazilian rainforest when he came upon a strange, organism which had yet to be classified. It was small, with a mass of only 10 grams. Bill noticed the organism was coverd in feathers. After further investigation, Bill discoverd that although it did not fly, it had hollow bones. How should Bill best classify this organism.
A.amphibian
B.bird
C.mammal
D.reptile