What is the difference between lossy compression and lossless compression?

• A. Lossless compression retains all original data.
• B. Lossy compression discards some data to reduce file size, while lossless retains all original data.
• C. Lossy compression increases data to improve quality.
• D. Both produce identical results in most cases.

Answer: (B)

The key idea is whether data is sacrificed to shrink the file. In lossy compression, some information is discarded to reduce size, so the decompressed file is only an approximation of the original and perfect recovery isn’t possible. In lossless compression, every bit of the original data is preserved, so you can reconstruct the exact original file from the compressed version.

That’s why this option is the best: it clearly contrasts discarding data with preserving all data. The other statements are not accurate: lossless does keep all data, but that alone doesn’t explain the difference; claiming data is increased to improve quality is false; and saying both give identical results ignores the actual loss in lossy compression.