Final answer:
Krakauer attributes Scott Fischer's fatigue on summit day to illness from a persistent gastrointestinal parasite, and not to poor conditioning, inexperience, or lack of motivation.
Step-by-step explanation:
In Jon Krakauer's account of the 1996 Mount Everest disaster, he offers an explanation for Scott Fischer's fatigue on summit day. Krakauer posits that Fischer's weariness was due to being sick with a gastrointestinal parasite, which he had previously contracted. This condition had not been fully resolved and reemerged when his immune system was under the stress of high altitude and extreme exertion. Krakauer did not attribute Fischer's fatigue to poor physical conditioning, lack of experience, or a lack of motivation.