If the options are metaphor, alliteration, allusion, and apostrophe, I believe the answer is metaphor, because the others don't fit.
Alliteration is the repetition of a consonant.
Allusion is reference to something or somebody outside of that literary work.
And apostrophe is the author speaking directly to somebody outside the poem, usually gods or a muse.
It's more important to what a person does because as they say, actions speak louder than words do. A person can think a certain way but not act on it but what a person does reflects what they decide internally and what they wanted to do with that idea externally showing that they are serious with that idea of theirs in their head.
