这题应该选A选项啊
What he said at the meeting 是一个主语从句,他在会议上所说的话使在场的每个人都很惊讶.
如果用that,that可以引导主语从句,但是在主句从句中不充当任何成分,所以That he said at the meeting 中said仍缺少宾语.
而the fact和the matter 作主语的话,后面he said at the meeting 就是一个定语从句,但是 是不能搭配 said the fact/matter 的
所以这题应该用what的