What does the following command in netcat do?
nc 55555 < /etc/passwd

A.
loads the /etc/passwd file to the UDP port 55555

B.
logs the incoming connections to /etc/passwd file

C.
deletes the /etc/passwd file when connected to the UDP port 55555

D.
grabs the /etc/passwd file when connected to UDP port 55555

Explanation:
-l forces netcat to listen for incoming connections.
-u tells netcat to use UDP instead of TCP
-p 5555 tells netcat to use port 5555
< /etc/passwd tells netcat to grab the /etc/passwd file when connected to.