Choose all of the characteristics from the list below that are examples of adaptations common among all birds.




(1) backbone


(2) cold-blooded


(3) give live birth to offspring


(4) sharp teeth


(5) solid bones


(6) four legs or feet


(7) feathers


(8) hollow bones


(9) warm-blooded


(10) four-chambered heart


(11) lay hard-shelled eggs


(12) two legs or feet


(13) soft-shelled eggs


(14) two-chambered heart