Answer: In the air sacs
Explanation: Air sacs has a million tiny holes that is were oxygen transfers. Inside the air sacs oxygen moves across paper thin walls to tiny blood vessels called capillaries into your blood
The oxygen enters the bloodstream from the alveoli.
When it involves granting favors it's called quid pro quo.
Extension exercises are exercises that benefits the triceps. The exercise involves bending the elbow and extending the arms in repetitive motion. Triceps are parts of the arms which runs from the shoulder down to the back of the elbow. Answer is B