Answer:
a. enjambment
Step-by-step explanation:
When lines of poetry are run from one line to the next without including punctuation marks like commas or periods, such practice is referred to as an enjambment.
It is a literary device that poets use when they want to create a flow of thought across lines. It brings about fluidity in such poems and provides a narrative that is complex.
Like in the poem given above, the idea of the soul being unto itself is projected or stretched further into the next line.