Concept:State creation in Nigeria under military rule.Explanation:In May 1967, the military government headed by General Yakubu Gowon re-organised Nigeria by splitting the existing four regions into twelve states.This was done to address fears of domination by a single region and to promote even development.Each of the newly created twelve states was placed under a military governor.Therefore, the officer responsible for this reorganisation was General Yakubu Gowon.Answer:A. General Yakubu Gowon