A Listener's Summary of a Speaker's Words Shows That the Listener

A listener's summary of a speaker's words shows that the listener correctly understood the speaker's message.Which of the following must be true?

A) The speaker used clear, simplified language.
B) The listener used active listening.
C) The speaker sent a clear message and the listener successfully received the message.
D) Either the speaker sent a clear message or the listener was able to interpet an unclear message successfully despite its lack of clarity.