B is the best choice.
Explanation: You would know that it's the best one, because Gina kept on trying after she failed; a perfect example of the theme, Never give up; challenges make us stronger. A is not correct, because Jim was just telling himself that ELA is hard, and he wasn't trying to make himself better. C is not correct, because it says Cameron never studied, but his grades were strong, and he never failed a test. It doesn't say anything about persistence.