Which of the following is essential when preparing for a climbing expedition?

Leaving a detailed itinerary with a reliable person is crucial when preparing for a climbing expedition. This practice enhances safety and accountability. If something goes wrong during the climb or if climbers do not return as expected, having this information allows rescuers to respond more effectively. The itinerary should include details such as the planned route, expected return time, and any other pertinent information regarding the climbers and their equipment.

In contrast, while having experienced climbers can contribute to a safer expedition, limiting the group solely to experienced climbers does not guarantee safety or preparedness. Similarly, selecting climbs that exceed one's ability can lead to dangerous situations, and relying solely on verbal communication can introduce potential misunderstandings or miscommunications. A written itinerary serves as a clear and reliable point of reference for both the climbers and the people monitoring their safety.