What do poets use to "pack in more meaning per word"

Use a bigger word to be more explanatory.

the correct answer is d. a discussion of specific uses of alliteration

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when you are critiquing or evaluating a poem, you will mostly pay attention to the theme, as well as figures of speech and rhythm. alliteration is a figure of speech where consonants are repeated in neighboring words - and it is important for analysis of sound and rhythm, which is why it might appear in the evaluation of that poem.