Which of the following does not characterize the lungs of birds?
a) they expand during exhalation.
b) air flows unidirectionally through them.
c) they are compressed during inhalation.
d) there is gas exchange in the parabronchi.
e) they are smaller than those of a similar-

C) They are compressed during inhalation.

Explanation:

Birds breathe through rigid lungs that are located in the animal's thoracic region. The trachea of birds divides into bronchi that branch inside the lungs into very thin tubes called parabronchials or parabroncholes, which are irrigated by blood capillaries that allow gas exchange.

In birds there are no pulmonary alveoli (as in mammals), but air capillaries that depart from the parabroncholes. Oxygen gas passes from these capillaries to the blood capillaries, thus causing gas exchange.

In the lower portion of the bird's trachea, before branching the bronchi, we can find the syringe, a bag-like structure that has vocal cords responsible for the birds' scream and song. Most of the time, the sound emitted by birds serves to attract the mate, mark territory and prevent birds of the same species against some predator or other danger.