Concept:ECOWAS is an economic union of West African states, and its effectiveness is limited by certain structural and socio-cultural challenges.
Explanation:ECOWAS member countries include both Anglophone, Francophone, and Lusophone nations.
These nations differ in their official languages, such as English, French, and Portuguese.
This linguistic diversity creates a major language barrier in communication during meetings and trade negotiations.
Even though the listed problems like conflict of interest and financial issues exist, the language barrier is a unique and recognized major challenge of ECOWAS.
Hence, the question tests the specific problem associated with ECOWAS cooperation.
Answer:D. Language barrier