If a diff shows '2,4c2,4', what does this indicate about the change?

• A. Append after line 2
• B. Delete lines 2-4
• C. Replace lines 2-4 in the original with lines 2-4 from the new file
• D. Copy lines 2-4 from the first file to the second

Answer: (C)

In diff notation, a change operation signals that a section of the original file is being replaced by content from the new file. The two ranges show which parts are involved: the portion from the original that will be replaced, and the portion from the new file that will replace it. So a change instruction means you take the specified block from the new file and substitute it for the corresponding block in the original. It is not an append or a simple delete, and there isn’t a separate copy operation here. This is why the interpretation is that the original segment is replaced by the new content.