While performing a ping sweep of a subnet you receive an ICMP reply of Code 3/Type 13 for all the pings sent out.

What is the most likely cause behind this response?

A.
The firewall is dropping the packets.

B.
An in-line IDS is dropping the packets.

C.
A router is blocking ICMP.

D.
The host does not respond to ICMP packets.

Explanation:
Type 3 message = Destination Unreachable [RFC792], Code 13 (cause) = Communication Administratively Prohibited [RFC1812]