已知某期刊信息库中有作家信息表author（作者编号aid，作者姓名aname，作者笔名ausername，作者邮箱aemail，备注remarks），稿件表manuscript（稿件编号mid，标题mtitle，作者编号aid，交稿时间mtime）现需要设置外键作者编号，下列语句正确的是（） A ALTER TABLE manuscript ADD CONSTRAINT FK_aid FOREIGN KEY (aid) REFERENCES author (aid) B ALTER TABLE manuscript ADD FOREIGN KEY (aid) REFERENCES author (aid) C ALTER TABLE manuscript ADD CONSTRAINT FK_aid FOREIGN KEY (manuscript.aid) REFERENCES author (aid) D ALTER TABLE manuscript ADD FOREIGN KEY (manuscript.aid) REFERENCES author (aid)