Two opposing mechanisms determine alveolar expansion: leads to alveolar expansion while opposes alveolar expansion.
select one:
a. lung recoil; positive pleural pressure
b. positive pleural pressure; lung recoil
c. lung recoil; negative pleural pressure
d. negative pleural pressure; lung recoil

The correct answer is option d.

Explanation:

There are two contrary mechanisms, which determine alveolar mechanisms. These are negative neural pressure, which results in alveolar expansion, while lung recoil opposes alveolar expansion.  

The negative pleural pressure refers to the pressure inside the cavity that is marginally less in comparison to the atmospheric pressure, and at rest, the negative pleural pressure results in the expansion of lungs, while the elastic recoil phenomenon of the lungs opposes the alveolar expansion.