The answer is A. This is correct because when it gets cold enough, the water vapor in the air (Which is a gas) will condense onto any items. This is why there is dew on everything in the morning.
Based on the speech, it's safe to assume that President Lincoln use :C. Logical appeal
You can see how he analyze the Constitution and dig out its meaning to give an explanation to his audience
hope this helps
I think it's optimistic because he's saying to take the country back.