The African Union (AU), which replaced the Organisation of African Unity (OAU) in 2002, was established with the central objective of promoting co-operation and economic development among its member states. The AU's Constitutive Act sets out goals that include accelerating political and socio-economic integration of the continent, promoting peace, security, and stability, promoting sustainable development, and fostering international cooperation.
The other options are either inaccurate or describe other organisations entirely. Regulating business transactions within the international community is more aligned with organisations like the World Trade Organisation (WTO). Overseeing the free flow of political engagement between Africa and developed nations does not accurately describe the AU's mandate - the AU focuses on intra-African cooperation. Settling disputes among South East Asian countries is the concern of ASEAN (the Association of Southeast Asian Nations), not the African Union.
The AU currently has 55 member states encompassing the entire African continent and works toward continental unity, collective development, and the resolution of African challenges by Africans themselves.