Which of the following files needs to be changed in order to enable anonymous FTP logins with vsftpd?

Which of the following files needs to be changed in order to enable anonymous FTP logins with
vsftpd?

A.
/etc/vsftpd/ftpd.conf

B.
/etc/ftpd.conf

C.
/etc/vsftpd/anon.conf

D.
/etc/vsftpd.conf

E.
/etc/vsftp/ftp.conf