Lossy data compression is defined as which statement?

• A. A form of data compression in which none of the original data is lost.
• B. A form of data compression that preserves all data.
• C. A form of data compression using relatively high ratios that results in permanent loss of information upon reconstruction.
• D. A method of data backup.

Answer: (C)

Lossy data compression reduces file size by discarding information that is deemed less important for the end result. Because that discarded information cannot be recovered, the reconstructed data is not identical to the original—the loss is permanent. This trade-off allows much smaller files, especially at higher compression ratios, but can introduce artifacts or degradation in quality. This contrasts with lossless compression, which preserves all data and allows exact reconstruction. The option about data backup describes a different concept entirely.