"To come all that way, rifle in hand, with two thousand people marching at my heels, and then to trail feebly away, having done nothing—no, that was impossible."

What purpose does the end phrase separated by the em dash serve in this sentence?
Edit: The correct answer is "The phrase is meant to simplify and clarify the author's first thought." I'm 100% sure got full points for it on quiz.
For points just answer with "C. The phrase is meant to simplify and clarify the author's first thought."

Depending on the message displayed in the graffiti it can be taken as art or vandalism, as graffiti is a crime normally because people tend to tag places with signs from their gangs. I believe graffiti is art, I know most people don't take it that way but if someone makes something really cool and people enjoy it, it is art. The name graffiti is run into the ground, but if you look at the art people make with it when they aren't representing a gang or club, their work is modern art at its finest.