An administrator is uncomfortable allowing users to log in as root. Which of the following ensures that root logins are disallowed? 

Answer options:

A. usermod -L root
B. usermod -G root
C. usermod -B root
D. usermod -U root

B

Reference: https://web.mit.edu/rhel-doc/4/RH-DOCS/rhel-sg-en-4/s1-wstation-privileges.html