Arrange the following four choices from proximal to distal of the trachea [truth-KE-uh]: bronchiole [BRONG-kee-ohl], alveolar [al-VEE-uh-ler] sac, primary bronchus, alveolar duct.
3, 1, 4, 2 (ACCEPT: PRIMARY BRONCHUS, BRONCHIOLE, ALVEOLAR DUCT, ALVEOLAR SAC)