Hello!
One of the main purposes of the closing section of a cover letter is
![\boxed{ \bf To~let~the~reader~know~how~he~or~she~can~contact~you.}](https://img.qammunity.org/2019/formulas/english/high-school/oh44kk09xvq66kqkqzdhl3iyse6wjriv2i.png)
The closing section usually lets the reader know how they can contact the writer. For example, via email, telephone, an arranged meeting, etc. The correct answer is option c.