Question

leaf like piece of cartilage that closes the opening into the larynx during swallowing; prevents food and liquids from entering the respiratory tract

Explanation:

The epiglottis is a leaf - shaped cartilage. During swallowing, it covers the larynx opening to stop food/liquids entering the respiratory tract. Bronchioles are small airways, bronchi are larger airways, and alveoli are gas - exchange sacs. Only the epiglottis matches the described function.

Answer:

epiglottis