Which phrase from the poem “we real cool” by gwendolyn brooks is an example of alliteration?

“thin gin”
“pool players”
“die soon”
“we/jazz”

Alliteration is a figure of speech in which two neighboring words begin with the same consonant - alliteration is basically the repetition of the same non-vowel letter at the beginnings of adjacent words. 
Having this in mind, the phrase from the poem “We Real Cool” by Gwendolyn Brooks which is an example of alliteration is the second one - "Pool Players."

Be a little more specific