We can actually deduce here that the line from "Monet’s ‘Waterlilies’" by Robert Hayden that best demonstrates the speaker’s regret about the effects of violence and destruction in the world is: "Here is the shadow of its joy".
Speaker's regret actually refers to what makes the speaker of the story or poem to feel sad and repentant about something or a situation.
We can actually see here that "here is the shadow of its joy" is the line that shows the speaker's regret.
Learn more about the speaker on https://brainly.com/question/23859407
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