In a diff output, what does a line starting with '<' denote?

• A. It corresponds to a line from the updated file
• B. It marks a line to be deleted
• C. It indicates a line from the original file
• D. It indicates a context line unchanged

Answer: (C)

In a side-by-side diff, the left side represents the original file. A line that starts with a less-than sign is a line that exists in the original file at that spot. It shows what was there before the change, and you compare it to the corresponding line on the right (the updated file) to see what was added, removed, or changed. If there’s no matching line on the right, that original line was deleted; if there’s a different line on the right, that’s what replaced it.