Is there more to the question
You need to get on top of your stuff.
you need to stay in school and get good grades and if you have a hard time with that then you need to take notes and study. a lot.
you need to focus on your career after college and don't let anyone get in your way or you won't get where you deserve to be.
Answer:
C
Explanation:
This would not be a good concluding sentence because it changes the point of view of the narration from the third person to the first person.
More importantly, this option changes the tone of the concluding sentences from semi-form with an informative style to informal with a conversational style. The changes does not favor the well-structured paragraph and would take away from the general message understood from reading it.