In this poem by John Donne, he speaks to his lover about how he must leave and she must not be sad about it, for their love would always bind them together. In his text, he compares themselves to a compass and how they are two parts of a whole. In the last stanza, which is quoted in your question, he explains how her firmness as one of the feet in a compass helps him draw a perfect circle, and end right where he begun. Therefore, the best answer would be D.
