Which of the following commands, when issued from a non-root user, will remove all files…?

Which of the following commands, when issued from a non-root user, will remove all files from the /tmp directory after prompting the user for the root password?

A.
su "rm -rf /tmp/*"

B.
rm -rf /tmp/* -su

C.
su -c "rm -rf /tmp/*"

D.
rmdir -rf /tmp/*