Answer the following question given this paragraph: Birds are endothermic tetrapod vertebrates. They are bipedal and have wings and feathers. Their organ systems are adapted for flight. For example, they have light-weight air-filled bones and a large four-chambered heart. Birds also have relatively large brains and a high level of intelligence. Q: In birds, lightweight air-filled bones and a large four-chambered heart are examples of adaptations for what purpose? Choices: - speed - long lifespan - mating - flight A:
Answer:
flight