The best choice is (D) 3 and 4.
Detail 3 states that European powers were required to prove a substantial presence in an area before establishing a colony, which indicates a regulation meant to benefit them by creating a structured method for colonization that could minimize conflict.
Detail 4 highlights that once these regulations were established, colonization rapidly succeeded, leading to almost complete control of Africa by the Europeans within a short period. This illustrates that the regulations allowed European powers to effectively expand their control and benefit from the colonization process.
Together, these details support the idea that the regulations were designed to benefit European countries in their colonization efforts.