What did you --at yesterday 'meeting?A say B.speak C.talk D.

A
What did you say?这个应该是固定说法
...at yesterday's meeting 是时间状语
抱歉刚才的错误
我觉得可以从搭配上看
如果用talk的话,应该是talk about ( somnething【其实就是what指代的内容】)
如果是tell的话,后面应该有宾语,就是tell somebody
如果是speak,一般是speak to/at somebody.
如果描述内容的话,楼上的speak of可以
They spoke of the old days on the campus.他们谈起昔日的校园生活.
另外这个也可以提供你参照,四个词的区别