I’m thinking it’s going to be C
America's response to 9/11 abroad wasn't effective because it led to the invasion of a country (Iraq) that had absolutely nothing to do with it. The American public was deceived into thinking that the invasion was necessary to keep Americans safe.
Marx and Engels begin The Communist Manifesto with "A spectre is haunting Europe" because they wanted to warn the bourgeoisie and the elite class that their movement is strong and it is not going to stop until Europe is classless. Literary effect: the movement is mainstream. Political effect: the movement is powerful.