The level of oxygen in the blood...
the level of carbon dioxide in the blood...
the level of oxygen in the alveoli...
the shape of the alveoli...
the shape of the lungs....
Answer:
The legal obligation to safeguard others from harm while they are in your care, using your services, or exposed to your activities
Explanation:
For example: The school's duty of care towards its pupils
The letter states that the city council has a duty of care to road users to ensure that crossings are properly controlled.