What is the effect on the pulmonary artery pressure of training at altitude?
A. Increase in pulmonary artery pressure due to hypoxic vasoconstriction
B. Increase in pulmonary artery pressure due to thromboxane A2
C. Increase in pulmonary artery pressure due to endothelin
D. Decrease in pulmonary artery pressure due to nitric oxide
E. No change in pulmonary artery pressure because cardiac output does not change