Concept:The Yoruba Peace Treaty is a historical agreement signed to restore unity and peace across Yorubaland.Explanation:The treaty was signed on September 23, 1886.It was intended to end the internal wars among the Yoruba people.This treaty is an important document in modern Yoruba history.Its goal was to promote harmony and cooperation throughout all parts of Yorubaland.Thus, the year of the peace treaty is 1886.Answer:B. 1886