Which statements are true about helium and heliox mixtures? I. Helium is a gas that is denser than either air or oxygen. I. Heliox decreases the effective flow resistance in patients with upper airway obstruction. I.I f you use a flow meter calibrated for oxygen to deliver a 70:30 heliox concentation, the actual flow of heliox will be 1.8 times greater than the indicated flow. IV. Heliox can't be administered through a mechanical ventilator. A. I and IV only B. Il and II only C. Il and IV only D. I and Il only