Final answer:
Anyone with a VO2max under 50 ml · kg-1 · min-1 would likely have the greatest need for supplemental oxygen on Mount Everest as lower VO2max indicates reduced cardiovascular fitness and a reduced ability to cope with low oxygen levels at high altitudes.
Step-by-step explanation:
On Mount Everest, anyone with a VO2max under 50 ml · kg-1 · min-1 would have the greatest need for supplemental oxygen. VO2max is a measure of an individual's maximum rate of oxygen consumption during intense exercise and is a good indicator of cardiovascular fitness. The higher the VO2max, the more fit the individual is considered to be. Lower VO2max values correlate with a greater need for supplemental oxygen at high altitudes where oxygen levels are significantly reduced.
On high-altitude expeditions like those on Mount Everest, oxygen availability decreases with altitude due to lower atmospheric pressure. The body may experience hypoxia, an inadequate supply of oxygen to body tissues, which can lead to altitude sickness. Mountain climbers often rely on bottled oxygen to prevent hypoxemia and to maintain adequate oxygenation for bodily functions, especially if their VO2max is not sufficiently high to cope with the extreme conditions.