Concept:The question focuses on the federal ministers who served in the cabinet of Prime Minister Tafawa Balewa during Nigeria's First Republic.
Explanation:Alhaji Muhammadu Ribadu served as the Federal Minister of Defence in the Balewa administration.
Chief Festus Okotie-Eboh served as the Federal Minister of Finance under the same government.
Both men were among the most prominent federal ministers between 1960 and 1966.
Alhaji Adamu Ciroma and Chief Richard Akinjide are associated with later administrations, not the Balewa cabinet.
Chief Kolawole Balogun and Alhaji Umaru Dikko also came into prominence during subsequent governments.
Chief Aja Nwachukwu did serve under Balewa, but Alhaji Umaru Dikko did not, so option D fails.
Therefore, the only pair that completely matches the condition is the one in option A.
Answer:A. Alhaji Muhammadu Ribadu and Chief Festus Okotie-Eboh.