Lossless data compression is defined as which statement?

• A. A form of data compression in which some data is discarded to reduce size.
• B. A form of data compression in which none of the original data is lost when reconstructed.
• C. A form of data compression using very high ratios with permanent loss of information.
• D. A method of optimizing network latency.

Answer: (B)

Lossless data compression preserves every bit of the original data; after decompression you get exactly the same data you started with. This reliability is what makes lossless the right definition: no information is permanently discarded, so the reconstruction is exact. This is crucial for text, software, and other data where even a small change would be unacceptable. Formats like ZIP for general files and PNG for images use lossless methods, while formats like JPEG use lossy compression, which sacrifices some detail to achieve higher compression. Lossy compression achieves higher reductions but at the cost of irretrievable information, and optimizing network latency is a separate concern not defined by these compression types.