The idea being tested is the tendency to misjudge how close you are to the real summit in extreme high-altitude conditions. On Everest, the topography can create false peaks and deceptive cues near the final stretch, and fatigue, wind, and poor visibility make it easy to mistake a high point for the true summit. In this case, the Indo-Tibetan expedition pushed upward with the belief they had reached the summit, but they had not. The terrain and perspective at that height can make the true summit lie just beyond what looks like the top, so their search didn’t line up with where Hansen, Hall, or Lopsang actually were. That misperception explains why they failed to find those climbers during the push.

Total fatalities on Everest in 1996 is the key idea here. That year a powerful storm hit during the climbing season, affecting several expeditions and leading to multiple deaths across the different teams. When you add up all the climbers who died on the mountain that year, the widely cited total is fifteen. This figure is the standard tally you’ll see in histories of the disaster and in study materials, and it’s the reason it’s the best answer. Numbers like ten or twenty or twenty-five don’t match the established total because they either underestimate or overstate the number of fatalities recorded for that season.

At high altitude, acute mountain sickness commonly shows a cluster of symptoms that Krakauer notes: headaches, dizziness (often described as vertigo), trouble sleeping (insomnia), and a reduced appetite. These four fit the pattern he observes as climbers ascend, with headache and dizziness being prominent, along with sleep disturbance and appetite loss. The extra item about cuts and scrapes not healing is not a symptom of altitude sickness and serves as a distractor. The other options include signs that aren’t typical for altitude sickness, such as rashes or thirst, or mix in symptoms that point to other conditions (fever with diarrhea, or coughing up blood), which are not representative of the common AMS pattern Krakauer describes.

Managing oxygen use is crucial on extreme altitude descents. Oxygen becomes a precious resource, and climbers often conserve by limiting flow when it isn’t needed for every moment of movement. Krakauer’s request to Harris to turn off his oxygen valve reflects this mindset: cutting off oxygen when it isn’t actively required helps preserve the remaining supply for the dangerous parts of the descent and for others who still depend on it. In the harsh conditions they faced, every bit of saved oxygen could make a real difference in safety. Taking a photo would distract from immediate safety, and bagging a rock for proof isn’t relevant to the descent’s needs. Turning up the oxygen flow would waste scarce supply, not conserve it.