What does this source address signify?

Frank installed Wireshark at all ingress points in the network. Looking at the logs he notices an odd packet source. The odd source has an address of 1080:0:FF:0:8:800:200C:4171 and is using port 21.

What does this source address signify?
A . This address means that the source is using an IPv6 address and is spoofed and signifies an IPv4 address of 127.0.0.1.
B. This source address is IPv6 and translates as 13.1.68.3
C. This source address signifies that the originator is using 802dot1x to try and penetrate into Frank’s network
D. This means that the source is using IPv4

Answer: D