What should you pay close attention to when analyzing a story's theme? the plot
the setting
the author
the main character

That which you should pay close attention to when analyzing a story's theme is the plot.

The theme of a story refers to the central message of the text. The central message of the text could be about love, conformity, growing up, etc. The plot of the story which contains details about the story will be useful in revealing the theme of the text.

So, that which you should pay attention to when analyzing a story's theme is the plot.

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b is the answer