Concept:The African Union’s biggest obstacle is political disunity rather than any lack of resources or labour.
Explanation:The AU frequently struggles with tensions and political discord among its member states.
Member countries often disagree over border disputes, leadership rivalries, and regional influence.
Such disagreements prevent the union from speaking with one voice.
They also weaken its ability to intervene effectively in conflicts and peacekeeping missions.
Africa is well endowed with rich natural resources, so option D is incorrect.
The continent has a large and growing labour force, ruling out option C.
Option B refers to "inter-ethnic extinction," which is not a recognised challenge of the AU.
Therefore, the major challenge facing the AU is political disagreement among member states.
Answer:A. tensions and political discord among member states