I am writing to apply for the customer service representative position that was advertised on your company's website. What makes the style of this effective?

This style of writing is effective because:

The writer specifically indicates the vacant position (customer service representative) and the media (company's website) from which the vacancy information is obtained.

Explanation:

The first paragraph of an effective application letter should make reference to the subject under discussion.  It is also proper for the applicant to indicate how she obtained the information for her application.  The reference demonstrates that the applicant had done her background study and is also applying to fulfill the company's requirements.

scholarship is an sc because, by definition, a subject complement is the adjective, noun or pronoun that follows a linking verb, for example the verb be (in any of its forms).