What is necessary to prevent duplicating efforts among responders?

The correct choice highlights the importance of knowing where each organization is operating and the locations of their offices. This information allows responders to coordinate their efforts effectively, ensuring that they do not overlap in the areas they serve. By having a clear understanding of each organization's operational footprint, responders can identify gaps in service provision and focus on reaching communities that may be overlooked. This type of coordination minimizes redundancy and maximizes the efficient use of resources, ultimately leading to a more effective humanitarian response.

In contrast, while names of volunteers and the total budget could provide some context, they do not directly facilitate the coordination of field operations. Future plans for recovery efforts are important, but they become relevant primarily after immediate response needs have been addressed. Therefore, knowing the operational locations is essential for real-time collaboration among humanitarian organizations.