4. How does respiratory mucus help to protect your body?
A. Dust and harmful bacteria are filtered in the mucus and purified so that they can travel through the body with ease.
B. Dust and harmful bacteria penetrate the mucus, making it stronger and more protective as time goes on.
C. Dust and harmful bacteria that are inhaled stick to the mucus so that it never enters the rest of the respiratory system.
D. Dust and harmful bacteria react with the mucus so that it can be swallowed more easily and not brought to the lungs.