Question

climbing mount everest is a physically demanding and dangerous undertaking even for experienced mountaineers. consider the term climbers use for the area of the mountain above twenty - six thousand feet. they call it the \death zone.\ the air at that altitude is so thin that most climbers must rely on bottled oxygen to remain alert and alive. but the challenges of such a grueling climb begin long before mountaineers reach that high altitude. lower down on the mountain, climbers must conquer a risky obstacle known as the khumbu icefall. this enormous sheet of dangerous ice dares climbers to navigate it without falling through large gaps hidden in the ice and snow.
based on the passage, why is the area on everest above twenty - six thousand feet so dangerous for climbers?
because of the large, hidden gaps in the ice and snow
because of the lack of sufficient oxygen in the atmosphere
because of the lack of a clear route to navigate
because of the huge sheet of ice called the khumbu icefall

Explanation:

To solve this, we analyze each option by referring to the passage:

• Option 1: The large, hidden gaps in ice and snow are related to the Khumbu Icefall (lower on the mountain), not the area above 26,000 feet. Eliminate.
• Option 2: The passage states "The air at that altitude is so thin that most climbers must rely on bottled oxygen...", showing lack of sufficient oxygen makes the area above 26,000 feet dangerous. This matches.
• Option 3: The passage does not mention a lack of clear route for the area above 26,000 feet. Eliminate.
• Option 4: The Khumbu Icefall is lower on the mountain, not in the area above 26,000 feet. Eliminate.

Answer:

because of the lack of sufficient oxygen in the atmosphere