The air-filled sac like structures at the end of the bronchial tree is called ____.

A. alveoli

Alveoli are the sac like structures at the end of the bronchial tree, this is where gas exchange takes place

Bronchioles: Branches of the bronchi, conduct air to the alveoli
Trachea: tubular structure, conducts air from the larynx to the bronchi
Bronchi: tubular structure, branch of the trachea, conducts air from trachea to bronchioles