Answer the following question given this paragraph: 

Functionally, the respiratory system can be divided into a conducting zone and a respiratory zone. The conducting zone of the respiratory system includes the organs and structures not directly involved in gas exchange. The gas exchange occurs in the respiratory zone.


Q: The conducting zone of the respiratory system includes the organs and structures not directly involved in what?

 Choices:

- copper exchange

- helium exchange

- gold exchange

- gas exchange

A:
gas exchange
