Question: What would this sed command do?

1. It would substitute the letter with an ampersand (&).
2. It would replace all letters in the textfile.txt file with ampersand (&).
3. It would replace the first four letters with an ampersand (&).
4. It would place parentheses around the first four letters of each line of textfile.txt.

Answer: The correct answer of the above question is Option C:It would replace the first four letters with an ampersand (&).