An administrator is adding an existing user named "buddy'' to the Apache group. Which of the following should the administrator perform to accomplish this task?

useradd is used to create a new user account, not to modify an existing one.

The usermod command is used to modify an existing user's account details, including their group memberships. While `-aG` is typically used to add a user to a supplementary group, `-g` can change the user's primary group, and usermod is the correct utility for modifying an existing user.

useradd is used to create a new user account, not to modify an existing one.

The command `sudo usermod -g apachebuddy` is missing the username as an argument and would attempt to set 'apachebuddy' as a primary group for an unspecified user.