Concept:Choose the organisation that is a non-governmental body involved in West African agriculture.Explanation:Operation Feed the Nation, River Basin Development Authority, and Agricultural Development Project are all government-run programmes or agencies.The International Institute of Tropical Agriculture (IITA) is an international non-profit research organisation.It focuses on agricultural development and food security in West Africa, making it the non-governmental organisation among the options.Answer:D. International Institute of Tropical Agriculture