Which of the following structures are tubes?
A. Cilia, adenoids, mucous, epiglottis
B. Apex, base, hilum
C. Frontal, maxillary, sphenoidal, ethmoidal
D. Eustachian, pharynx, bronchi
A. Cilia, adenoids, mucous, epiglottis
B. Apex, base, hilum
C. Frontal, maxillary, sphenoidal, ethmoidal
D. Eustachian, pharynx, bronchi