Correct Option: D. Ethiopia and Somalia Detailed Explanation: The Organization of African Unity (OAU), which was established in 1963, aimed to promote unity and cooperation among African states and to resolve conflicts on the continent. One of the significant disputes that the OAU was involved in mediating was the conflict between Ethiopia and Somalia, particularly during the Ogaden War in the late 1970s.

1. Historical Context: The conflict between Ethiopia and Somalia primarily revolved around the Ogaden region, which is predominantly inhabited by ethnic Somalis. Somalia sought to annex this territory, claiming it as part of Greater Somalia. This led to military confrontations, notably the Ogaden War from 1977 to 1978, where Somalia invaded Ethiopia to claim the Ogaden region.
2. Role of the OAU: The OAU played a crucial role in mediating the conflict. It sought to promote dialogue and peaceful resolution between the two nations. The OAU's involvement was significant because it represented a collective African effort to address conflicts within the continent, emphasizing the principle of non-interference in the internal affairs of member states while also advocating for peaceful resolutions.
3. Outcome of Mediation: Although the OAU's mediation efforts faced challenges, they were part of a broader strategy to stabilize the Horn of Africa. The OAU's involvement highlighted the importance of regional organizations in conflict resolution and the need for African solutions to African problems.

Why Other Options Are Incorrect:

• A. Tunisia and Morocco: While there have been historical tensions between Tunisia and Morocco, particularly regarding territorial disputes and political differences, there has not been a significant conflict that required OAU mediation. The relationship between these two countries has generally been more cooperative than confrontational.
• B. Zimbabwe and Tanzania: Zimbabwe and Tanzania have had a generally positive relationship, especially during the liberation struggles in Southern Africa. Tanzania supported Zimbabwe's fight against colonial rule, and there has not been a notable dispute between the two that required OAU mediation.
• C. Kenya and Somalia: Although there have been tensions between Kenya and Somalia, particularly regarding issues like piracy and the Somali civil war's spillover effects, the OAU was not primarily involved in mediating disputes between these two nations. The conflicts have been more related to security and humanitarian issues rather than direct territorial disputes.

Summary of Key Points:

• The OAU was instrumental in mediating the conflict between Ethiopia and Somalia during the Ogaden War.
• The conflict was rooted in territorial claims over the Ogaden region, inhabited by ethnic Somalis.
• The OAU's mediation efforts emphasized the importance of African solutions to African problems.
• Other options (A, B, C) do not represent significant disputes that required OAU intervention.

This thorough understanding of the OAU's role in mediating the Ethiopia-Somalia conflict will help you grasp the importance of regional organizations in conflict resolution within Africa.