During gaseous exchange in the alveoli, what happens to nitrogen?

A

There is no net nitrogen exchange, as nitrogen is filtered out by the alveoli.

B

The nitrogen is absorbed by the alveolus to form amino acids.

C

The nitrogen is filtered out by the alveolus, as the nitrogen molecule is too large to cross the gaps in the capillaries.

D

There is no net nitrogen exchange, as the blood is saturated with nitrogen.