What is the significance of the variables csv$\_$file$\_$location and report$\_$file in the code snippet from the lab? csv$\_$file$\_$location $=\text{'}\text{'}$

report$\_$file $=\text{'}\text{'}+\text{'}/$updated$\_$user$\_$emails.csv$\text{'}$ They store the usernames for accessing a remote server.

They define regular expressions for email domain validation.

They store file paths for input and output CSV files.

They contain the old and new domain names for email address replacement.