What is your question what do you not get?
D. Because it talks about how you would not be able to enjoy the sport without the physics, however it says nothing on how scientific principals effect snowboarding.
In Chapter 7 Moonshadow went to visit Mrs. Whitlaw to educate her on demons. Moonshadow was impressed that Mrs. Whitlaw seemed to be interested in other people. He explained about the dragons and was impressed with the knowledge he possessed and she could see his point of view. After his visit, Moonshadow came home thinking that demons weren't that bad.
D is not your answer. Someone who is bitter and exhausted has learned something that made them bitter and exhausted. They have changed.
C is not your answer. We have a hook here. We're drawn in to find out why she is different. That's not a flat character.
A is not your answer. These twins have a conflict. It is a natural way to develop a story.
B as charming as he sounds, his charm and wit lead us nowhere. He is a foil for the main character. Our pleasure in him is only momentary. B is the answer.
