The instance of call and response in these lines can be seen in the first two lines of the text, where the speaker states that he will not drink the cup of bitterness and hatred and receives an answer from an audience soon after, who agrees with him.
The effect of this is to reinforce the sense of organization and support for a cause.
We can arrive at this answer because:
An instance of call and response occurs when a statement is presented in a text and is responded to shortly thereafter by another statement.
In the excerpt above, we can see that the speaker begins by declaring that he will not drink from the cup of bitterness and hatred.
Shortly thereafter, he is answered by an audience who declares "O Lord! Amen! Yes! Sure enough!"
This allows the audience to show support for the speaker's words and are willing to help him fight for the cause that is being established.
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