If I thought about keeping a diary, I would keep it to remember things I've done. (I have terrible memory so that's what I'm going for) But since this is an assignment I would probably go with the last one, D. (It seems kinda like something a person would write a diary for, like those girls in diary/books In example: D0rk Diaries. Most of them aren't popular in school and talk about the emotions they feel in their diaries.) Hope I helped a bit.