A bird’s nearly hollow bones help it to .
A) store extra oxygen
B) deliver oxygen to its cells
C) be lightweight in the air
D) defend itself against predators

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

i believe the answer is snake.

i think the answer is a.keratin is the pigment responsible for skin color.