A student downloads a compressed music file and then decompresses it.
Identify what is meant by decompression.
Mark scheme
- C Data is restored to its original format (1)
- The only correct answer is C. The correct answer is data is restored to its original format.
- A is not correct because encryption changes data so that it cannot be read without a key; it does not restore the data
- B is not correct because permanently removing data to reduce the file size is lossy compression, not decompression
- D is not correct because storing data using fewer bits is compression, not decompression
Example answers and how they were marked
Full marks1/1
C Data is restored to its original format
Why: Correct option (1).
No marks0/1
D Data is stored using fewer bits
Why: Near miss: this describes compression, not decompression.
No marks0/1
B Data is permanently removed to reduce the file size
Why: Misconception: this describes lossy compression, not decompression.