Representing Text, Sound, Images and Storage: Question 9

Worked solution

Why the other options are wrong

• (A) is incorrect: it swaps the two methods’ behaviour. Removing detail the user cannot easily perceive is closer to how lossy compression is sometimes justified for photos or sound, not a description of how lossless compression works, and lossy compression does not “remove all repeated data” either.
• (C) is incorrect: it reverses the usual relationship. Lossy compression typically achieves a greater reduction in file size than lossless compression, precisely because it discards more of the original data.
• (D) is incorrect: executable files can still be compressed with lossless compression (for example, a ZIP-style algorithm can shrink an installer), so lossless compression is a genuine compression method here, not simply “no compression.”

Why B is correct

Lossless compression reduces file size without permanently discarding any of the original data, so the file can be perfectly reconstructed. Lossy compression, in contrast, permanently discards some data to achieve a smaller file. An executable installer file is a sequence of precise program instructions and data; if even one instruction or value were altered or missing, the program could fail to install or run correctly, or could behave unpredictably. Because the installer’s data must remain exactly correct, lossy compression’s permanent loss of data is unacceptable, so only lossless compression is used.

Final answer

B. Lossy compression’s permanent loss of data risks corrupting the program’s instructions, so only lossless compression, which keeps every bit of the original file intact, is safe to use.