Scenario B: Saruman is suffering from exposure to carbon monoxide (CO). CO binds to hemoglobin just like oxygen does, but it binds much more tightly and basically prevents O₂ from binding to any irons on the hemoglobin that have CO bound to them (the hemoglobin is still there, but not available to carry O₂). At the current CO concentration, CO is bound to about 30% of the hemoglobin. Aside from being an evil wizard, Saruman is otherwise healthy. If nothing else changes (ventilation, cardiac output, metabolic rate), what will be the effect of the CO on ______ (compared to before the CO exposure) PO₂ at the right ventricle (mixed venous PO₂):
a) increased by 20 %
b) largely unchanged
c) decreased by 15 - 20 %
d) decreased by 40 - 50%