The statement that provides the most accurate investigation of why Ethiopia and Egypt have run into conflict over resource management is:
"Ethiopia's building of a dam on the Nile could impact Egypt's use of the Nile because they lie downriver."
This statement specifically addresses the core issue of the conflict, which revolves around the management of Nile river resources, particularly concerning water flow and accessibility for Egypt, as Ethiopia builds infrastructure (like dams) that can affect water availability downstream.