Which of the following commands should be used to list all of the active network interfaces on a system？（）

The local host on a small network is named Earth. There is also a remote host on the network named Saturn.  The system administrator of the network is in the /u/tmp directory of Earth， and starts an ftp to Saturn as root.  Which of the following sequence of commands issued from the local host， Earth， will：（）。
1.Change to the /u/new directory on Saturn.  
2.Check to see if there is an a.out file on remote host Saturn.
3.Transfer a.out from Earth to Saturn.