Answer: D) It shows Lincoln believes that both sides are equally to blame for leading the country to war because they refused to cooperate.
Explanation: In the given sentence from the speech in which Lincoln describes his perspective about why each side chose to go to war, we can see that he explains how both sides rathered war than "let the nation survive" and "than let it perish" respectively, so that shows that Linconln believes that both sides are equally to blame for leading the country to war because they refused to cooperate.