Which of the following is NOT a characteristic or shortcoming of packet filtering gateways?

A. The source and destination addresses, protocols, and ports contained in the IP packet header are the only information that is available to the router in making a decision whether or not to permit traffic access to an internal network.
B. They don't protect against IP or DNS address spoofing.
C. They do not support strong user authentication.
D. They are appropriate for medium-risk environment.