User A at Company A is trying to transfer files to Company B, using FTP. User A can connect to the FTP server at Company B correctly, but User A cannot get a directory listing or upload files. The session hangs. What are two possible causes for this problem? (Choose two.) 

Answer options:

A. Active FTP is being used, and the firewall at Company A is not allowing the returning data connection to be initiated from the FTP server at Company
B.B. Passive FTP is being used, and the firewall at Company A is not allowing the returning data connection to be initiated from the FTP server at Company
B.C. At Company A, active FTP is being used with a non-application aware firewall applying NAT to the source address of User A only.
D. The FTP server administrator at Company B has disallowed User A from accessing files on that server.
E. Passive FTP is being used, and the firewall at Company B is not allowing connections through to port 20 on the FTP server.

AC