Answer the following question given this paragraph: 

Common diseases of the respiratory system include asthma, pneumonia, and emphysema. All of them are diseases of the lungs. The main way to keep your respiratory system healthy is to avoid smoking or breathing in the smoke of others.


Q: Common disease of what system include  asthma, pneumonia, and emphysema?

 Choices:

- the fecal system

- the digestive system

- the glandular system

- the respiratory system

A:
the respiratory system
