4(a) Define (i) economic integration, (ii) bilateral integration, (iii) regional integration, and (iv) global integration.

(b) Under commodity agreements, we have OPEC. (i) What is the Organization of the Petroleum Exporting countries (OPEC), and (ii) briefly explain two functions/roles of OPEC. (iii) Is OPEC generally evaluated as successful or unsuccessful (cite and reference a source to support your point).