The last two paragraphs mainly imply that ______.

参考解析：

推理判断题。根据倒数第二段第一句“Davie thinks the rise in self-harm may not be due to a rise in unhappiness, but simply that this age group now sees self-harm as a more culturally acceptable way to express extreme sufferings.”可知，Davie认为，自残现象的增加可能并不是因为不快乐的增加，而是因为这个年龄段的人现在把自残看作是一种文化上更能接受的表达极端痛苦的方式及最后一段“If that is the case, it is all the more reason not to make self-harm seem more common than it really is.”如果是这样的话，那就更有理由不让自残看起来比实际情况更普遍。由此可知，最后两段主要暗示青少年需要来自外界的正确指导。故选C。