Final answer:
The correct answer is 'a) Conciliate,' which means to reconcile or pacify, fitting the context of attempting to resolve a dispute between two parties with opposed views.
Step-by-step explanation:
The question asks to choose between 'conciliate' and 'saturate' to best complete the sentence given the opposed views of two parties involved in a dispute. The correct answer is a) Conciliate, which means to stop someone from being angry or discontented; to placate; to pacify; or to reconcile. 'Saturate' would be incorrect as it means to fill something or someone completely with something until no more can be added, which does not fit the context of resolving a dispute.
The historical context provided references to the increasing tensions between Northerners and Southerners before the American Civil War, illustrating how hard it was to reconcile their sharply opposed views on the subject of slavery, thus reinforcing the appropriateness of the word 'conciliate' in this context.