Concept:Colonial rule brought both good and bad changes to Ghana (the Gold Coast).Solution:Formal (Western) education, with schools, literacy and training of teachers, clerks and doctors, was introduced and spread during colonial rule. It is a positive effect.Barter trade existed before colonisation and was replaced by money. Human sacrifice was a harmful practice that was abolished. Christian marriage is a change in custom brought by missionaries, not usually counted as a main benefit.Answer:Option B (formal education)