Concept:The Economic Commission for Africa (ECA) was created to promote economic cooperation among African states, and its key structural achievement is the establishment of a continental development bank.
Explanation:The ECA is a United Nations body focused on encouraging economic development in Africa.
Among its major accomplishments is the creation of the African Development Bank (AfDB) to mobilize resources for African development.
Option A is accurate because setting up the AfDB is widely recognized as a concrete, lasting achievement of the ECA.
Option B is wrong because the AfDB mainly serves African member countries, not non-members.
Option C is incorrect because solving balance of payments problems is not the ECA’s direct achievement.
Option D is also incorrect because closing the gap with rich nations remains an ongoing goal, not an achieved major milestone.
Answer:A. setting up of the African Development Bank (AfDB).