B
[解析] 搭配辨析题。undertake to do sth. 意为“答应,担任某事”,如:She undertook to finish the task by Friday. 根据原文:成员国答应寻求一切有利于地区货币一体化进程的国家政策,故选项B undertake符合题意。选项A commence意为“(正式)开始”,例如:Unfortunately, he commenced speaking before all the guests had finished eating. 选项C initiate意为“开始,着手(计划等)”,如:Who initiated the violence?(谁制造了混乱?)选项D try to do sth. 意为“尽力做某事”。