Which compression format is proprietary to WinRAR?

The correct answer is the RAR compression format. RAR is a proprietary file format developed by Eugene Roshal for WinRAR, a popular file archiving and compression utility. Unlike other formats mentioned in the choices, such as ZIP, TAR, and GZ, which are either open or widely used standards, RAR is specifically linked with WinRAR software and provides features such as recovery records, error correction, and high compression ratios. Therefore, RAR is exclusive to and optimized for use with WinRAR, making it distinct from the other compression formats listed, which are commonly supported by various archiving tools.