Answer:
The best answer is letter A. It uses sarcasm to explain how hard the quiz was.
Step-by-step explanation:
By definition, sarcasm is the use of ironic remarks to convey the opposite meaning of what is being said. Let's think about what the sentence says. There was a quiz; the quiz covered six chapters of European history. We can all assume the quiz was, therefore, a difficult one. Even if the questions were not too complex, six chapters are a lot to study and memorize. Now imagine a student who has just finished doing the quiz. He is stressed out, tired, from all the studying and the answering. Imagine his teacher said at some point, "Don't worry, guys! It is just a quiz." The student, remembering that remark, says to a classmate, " If that was just a quiz, then the six chapters of European history it covered were just postcards from someone's summer vacation." He means that was not "just a quiz". It was a difficult one. Just a quiz would be easy, like reading postcards. Six chapters of history are quite the opposite. The student is, clearly, using sarcasm.