Users have been unable to reach www.comptia.org from a Linux server. A systems administrator is troubleshooting the issue and does the following:

Based on the information above, which of the following is causing the issue?

A. The name www.comptia.org does not point to a valid IP address.
B. The server 192.168.168.53 is unreachable.
C. No default route is set on the server.
D. The network interface eth0 is disconnected.