Answer the following question given this paragraph: 

Respiratory diseases are diseases of the lungs, bronchial tubes, trachea, nose, and throat ( Figure below ). These diseases can range from a mild cold to a severe case of pneumonia. Respiratory diseases are common. Many are easily treated, while others may cause severe illness or death. Some respiratory diseases are caused by bacteria or viruses, while others are caused by environmental pollutants, such as tobacco smoke. Some diseases are genetic and, therefore, are inherited.


Q: Diseases of the lungs, bronchial tubes, trachea, nose, and throat affect what organ system?

 Choices:

- digestive

- skin

- heart

- respiratory

A:
respiratory
