The PAO₂ Depends on Which of the Following Factors

The PAO₂ depends on which of the following factors?
1) Ambient (atmospheric) pressure
2) Fractional concentration of inspired O₂
3) Level of V_A
4) Types of fuels burned (fat, protein, and carbohydrate)

A) 1, 2, and 3 only
B) 1 and 2 only
C) 3 only
D) 1, 2, 3, and 4