An article that appeared in March 2022 had the following headline, "South Africa wants single African currency to boost intra-continental trade".

a) Various criteria that predict the success of a currency area have been identified. Discuss these criteria with reference to the proposal of establishing a single African currency backed by the continent's central bank and monetary institute. (15)

b) The headline mentions a possible benefit of joining a currency union. However, various costs have also been identified in the literature. Briefly discuss these costs. (10)