What are the factors that affect gas transport during intense exercise?

The modification of the hemoglobin saturation curve is determinant of gas transport during intense exercise.
The reduction of the transit time through the respiratory system is a disadvantage of the increase in blood flow during exercise.
The increase in blood flow is the only mechanism for greater oxygen supply during exercise.
The effects of Bohr and Haldane are especially important during intense exercise or in hypoxic conditions.
a) Only statements I and II are correct.
b) Only statements II and III are correct.
c) Only statements III and IV are correct.
d) Only statements I, II, and IV are correct.
e) All statements are correct.