C. Germany's attack on Russia was similar to betraying all the rules of civilization.
Russia's intention was clearly aimed at making peace with Germany, otherwise they would not have signed the peace treaty. The fact that Germany then turned around and broke that treaty because of how horrible their leaders were, shows that they were not following established rules of civilization.
because giving them lower grades can decrease their confidence in how they did but if you give them feedback they can see how they can improve themselves