As a system administrator, you have received a file named 'logins.txt' containing a list of usernames. However, the usernames are separated by commas and you need them to be separated by newlines to process them in a script. Using the 'tr' command, how would you translate the commas into newline characters in a shell script?
tr -s ',' '\n' logins.txt
tr '\n' ',' < logins.txt
tr -d ',' '\n' logins.txt
tr ',' '\n' < logins.txt