Answer:
Cover letter is sent with the application to draw the reader's attention to your skills, so B is the correct answer.
Step-by-step explanation:
When we are applying on some vacant post, we want to make the employer know all about our skills and abilities which makes us different from all other candidates. In this regard, we need a way to draw the employer's attention to our abilities and skills which can lead us to get the job. So, with our application for requesting the job, we also write the cover letter which sums up all our skills and potentials for doing that job. Cover letter is an additional information which can be very beneficial for the candidate and also for the employer because it describes the candidate in detail. By reading the cover letter, the employer can easily decide whether he can approve the applicant or he should refuse him because the application or resume of the application does not have detailed description of the applicant.