As per the question, the statement that most appropriately sums up the 'second inaugural address' of president Abraham Lincoln would be 'A nation at war with itself cannot stand.' The key idea or primary concern that surrounds and dominates the entire address is that 'the nation can only withstand a war by standing as a whole' and with 'the progress of our arms, upon which all else chiefly depends.' <u>Lincoln encourages the people to take a united call by saying 'let us(symbolize togetherness) strive on to. . . bind up the nation's wounds' as 'the judgments of the Lord are true and righteous altogether</u>.' Thus, <u>option A</u> is the correct answer.
