It means that even it everyone is doing something wrong, it is not right. It is referring to peer pressure, don't do something just because everyone else it doing it.
Tone indicates the writer's attitude. Often an author's tone is described by adjectives, such as: cynical , depressed , sympathetic , cheerful , outraged , positive , angry , sarcastic , prayerful , ironic , solemn , vindictive , intense , excited.
I honestly think (A) makes most sense, though it would be better if you showed the paragraphs to make more sense of this question. I can only guess because there is no story, so I think its (A)! It relates to the title, "Aiden Goes Silent". So (A)...
LOLZ
1. somber/joyous
2.
3. slow/rapid
4.
5. plain/severe
6.
7.
D answer is gloomy,meaning to express depression