B. Do. B is the correct word for this sentence because are the others are grammatically incorrect
An officer (police officer) is someone who fights against crime, and helps prevent it from happening. A criminal starts crime, and causes trouble for the police officers.
To clearly state the main idea. The main idea is the reason for your paper. Hope this helps! :)
B. They are spies for the Nazis, and Anne suspects this.
I suggest you watch this video. It's only one minute and it explains a lot. Hope this helps!
https://www.khanacademy.org/math/ap-statistics/analyzing-categorical-ap/analyzing-one-categorical-va...