Pay special attention to the last statement before the question - "He is doing well in school and has a girlfriend who is also a medical student." This sentence is there to tell you that the student in question does not have a disorder; his life is going fine. Answers A, B, D, and E are all disorders, and answer C is "traits", not a disorder. Ergo, the correct answer is C.
While that is the best fit for the characteristics, it can’t be the correct answer. The question asked for a disorder and therefore any non-disorder answer is disqualified.