Answer:
b. It keeps alveoli from collapsing with breaths.
Step-by-step explanation:
Surfactants are highly surface active agents which are formed from a protein and lipid complex. It comprises of a hydrophobic and hydrophilic portion and its sole purpose is to control the tension at the air-liquid interface and thereby lower the surface tension. Surfactants are produced by the type II aveolar pneumocytes in the lungs.
Surfactants are needed in order to aid breathing and prevent straining oneself, it also prevents the lungs from collapsing during breathing, a term known as atelectasis.