Which Statement Best Describes Why O2 and CO2 Can Both

Which statement best describes why O2 and CO2 can both be exchanged simultaneously at the alveoli and pulmonary capillaries?

A) Blood in the pulmonary capillaries is high in both O2 and CO2.
B) Blood in both the alveoli and pulmonary capillaries is at equilibrium.
C) Blood in the alveoli is high in both O2 and CO2.
D) Nitrogen is at a high pressure in both the alveoli and pulmonary capillaries and drives the exchange of O2 and CO2.
E) Each gas acts independently and diffuses down its own partial pressure gradient.