Would you please be quiet?I couldn’t hear what the professor

Would you please be quiet?I couldn't hear what the professor is__.A saying B speaking

say 是及物动词,表示讲某事,说某事,强调的是说话的内容.如：do you want to say something?
say 有被动语态.
speak 作为不及物动词时,强调说话的这个动作而已.he spoke on the meeting 在会上他说话了.
作及物动词时,后面只能跟某种语言.比如,he speaks Chinese
speak 没有被动
从句中可以看出,强调说话的内容听不清,所以选A
再问： 如果是会议上发言用speak吗？
再答： 对