A security analyst is preparing to explain why a firewall failed to prevent a user who broke into the server room from hacking the server. Which statement offers the best explanation?

a.

The firewall failed to identify an attack signature and generate an alarm.

b.

The firewall failed to monitor network traffic and use the "prevent, detect, and react" approach to security.

c.

The firewall did not cause routers to terminate connections with suspicious sources.

d.

A firewall protects against external access, but they leave networks unprotected from internal intrusions.