单选题 Such benefits are predicted to be greatest for Germany and Austria, ______ retain the closest ties with the candidate countries.
A．which B．where C．who D．that

【正确答案】 A
【答案解析】[解析] 结构识别
此句所填之词应为一个引导非限定性定语从句的关系代词，因与主句用逗号分开且指代物，因此A为答案。