请教大全991. Although the manager agreed to a more flexible work schedule, he said that it must be posted on the bulletin board so that both management and labor will know what everyone is assigned to do.
(A) he said that it must be posted on the bulletin board so that both management and labor will know what everyone is
(B) he said it had to be posted on the bulletin board so that both management and labor knows what everyone is
(C) he said that they would have to post the assignments on the bulletin board so that management and labor knew what everyone was
(D) he said that the schedule would have to be posted on the bulletin board so that both management and labor would know what everyone was（A）
(E) saying that the schedule had to be posted on the bulletin board so that both management and labor would know what everyone had been
请问为什么选a啊?为什么可以用将来时啊?
搜索的结果只有一条，而且说得不清楚，望大家帮帮忙！