All users are reporting that they cannot connect to the SFTP server. The administrator runs a scan: 

Which of the following would allow the administrator to fix the problem? 

Answer options:

A. Allow SFTP connections on port 22 using /etc/sysconfig/iptables.
B. Allow SFTP connections on port 20 and 21 using /etc/sysconfig/iptables.
C. Allow SFTP connections on port 25 using /etc/sysconfig/iptables.
D. Allow SFTP connections on port 1456 using /etc/sysconfig/iptables.

A