Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration because of

Lungs are made up of air-filled sacs, the alveoli. They do not collapse even after forceful expiration because of

Option 1 : Residual volume
Option 2 : Tidal volume
Option 3 : Expiratory reserve volume
Option 4 : Inspiratory reserve volume