An outline will help a lot. For example if you were Writing a paper on the French revolution it would look like this.
French Revolution
I. Intro parahgraph
II. Reasons Why the war started
A. the unequal system of taxation
B. The way that the peasants lived a life of poverty while the Nobles
lived a life of luxury just because of their title.
And so on
Answer:
1.an
I only know of 1 so please don't report me. I gave of 1 also so it can help you.
A isn't correct because it would be Is
C would be were
so the correct answer is B Because Don't agrees with the subject