What seems to be wrong?

You have compromised a server on a network and successfully opened a shell. You aimed to identify all operating systems running on the network. However, as you attempt to fingerprint all machines in the network using the nmap syntax below, it is not going through.

invictus@victim_server.~$ nmap -T4 -O 10.10.0.0/24 TCP/IP fingerprinting (for OS scan)

xxxxxxx xxxxxx

xxxxxxxxx. QUITTING!

What seems to be wrong?
A . The nmap syntax is wrong.
B . This is a common behavior for a corrupted nmap application.
C . The outgoing TCP/IP fingerprinting is blocked by the host firewall.
D . OS Scan requires root privileges.

Answer: D