D - Although I have a lot of friends, there are only a few people at
school who have really seen the true me.
Explanation:
This sentence best summarizes the work ahead, introducing the idea that he will discuss his friends, and the few people who have seen his true self. A makes sense for the subject, but introduces the topic too early for it to make sense. B makes an unrelated point, and would not work as a topic sentence but as an end point. C... I honestly don't know what this option says.
