close to prevent further damage. stop producing mucus. become clogged. become efficient.
I gave my students this multiple choice question: The cilia in the respiratory system are responsible for preventing dirt and mucus from entering the bronchial tubes and lungs. If the cilia are damaged, the person's bronchial tubes and lungs are most likely to

Only one answer is correct among these 4 choices:
- close to prevent further damage.
- stop producing mucus.
- become clogged.
- become efficient.

Could you tell me which one is correct?

become clogged.