You run Windows Defender on your computer and receive the following warning message： "Windows Defender Definitions havent been updated." You need to ensure that Windows Defender definition files are updated. What should you do？（）

A. Restart the Windows Defender service.
B. Repair the Microsoft Location Finder program.
C. Download and install the appropriate files from Microsoft Windows Update.
Download and install the latest Windows Defender application from the Microsoft Web site.