Answer:
c.He is not very professional and is not interested in the job.
Explanation:
In the business world integrity is the most important part. It shows the person's behavior, ability, work-efficiency. There should be the dressing sense, how you talk, the way you speak demonstrates integrity, learning practice, organizational ethics, writing skills, etc.
Accordingly, according to the case, Nathan recruits a summer intern and he selected one letter of introduction from the applicant and Nathan established three miswrite showing the applicant's non-interest and unprofessional internship. Thus he need to check before submitting the letter.