Read the excerpt below and answer the question.
 
Because I think a woman who is undecided between two offers, has not love enough for either to make a choice; and in that very hesitation, indecision, she has a reason to pause and seriously reflect, lest her marriage, instead of being an affinity of souls or a union of hearts, should only be a mere matter of bargain and sale, or an affair of convenience and selfish interest.

In this excerpt from "The Two Offers," Harper is making a connection between marriage and what other prominent theme of the time?

 business
 imprisonment
prostitution
slavery