In what way did the plot make you feel? Don't summarize the plot, assume the reader knows generally what happened. Focus instead on specific points of the plot, describe what it was that happened and how it made you feel. Explain if it made you question a belief or if it resonated with and experience you've had. It's basically a personal statement, so be direct.
Example: Did you know that donating blood is actually good for your health? It is true! When you donate blood, your iron remains maintained at a healthy level. Reduction of iron in your body can lead to cancer, and no one wants that! Plus, donating blood reduces the risks of heart and/or liver ailments.
No, a cover letter is not always a advertisement, so it could be true OR false. But based on your question, I'd say true.
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a
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d
I think this is correct. I don't know honestly.