Final answer:
The poet Nikki Grimes uses enjambment in the excerpt from "Jabari Unmasked", a technique that allows a sentence to continue beyond the end of a line without a terminal punctuation mark.
Step-by-step explanation:
The graphical element that the poet Nikki Grimes uses in the excerpt from "Jabari Unmasked" is C. enjambment. Enjambment occurs when a sentence or clause runs onto the next line without a pause or punctuation, contributing to the poem's rhythm and creating a sense of continuity. This technique often affects how readers interpret the lines and encourages them to move quickly from one line to the next, thus maintaining the flow and thematic linkage within the poem.