Read the excerpt from "Everest Then and Now." The increase in popularity means that more people are climbing Everest than ever. It's true that the economy of Nepal benefits from the hundreds of climbers each year. The government requires climbers to purchase a climbing permit. Climbers who hire Nepalese guides are also helping the local economy. However, more climbers on the mountain cause a number of problems. Large numbers of climbers on the mountain at once can be unsafe, especially when teams get close to the top of the mountain. This was not a concern in the early days of Everest explorers. Now, hiking companies encourage climbing teams to take turns when they get close to the peak. Climbers put in too much effort to get caught in a traffic jam near the summit.

What other information would help explain why traffic jams at the top of the mountain should be avoided?

Information about being respectful to other climbers on the mountain and how people should treat one another
Information about how traffic jams put dangerous chemicals into the air that destroy the air quality on the summit
Information about the dangers that can occur when too many people gather on the summit at one time
Information about the number of climbers who make it to each camp on the mountain, including the base and the summit