The synthesis above used bromobutane, but acetylene is the only allowed source of carbon atoms. Using the reagents given, identify a synthetic route for the production of bromobutane from acetylene. The transformation above can be performed with some reagent or combination of the reagents listed below. Give the necessary reagent(s) in the correct order, as a string of letters (without spaces or punctuation, such as "EBF"). If there is more than one correct solution, provide just one