What type of system monitors and controls incoming and outgoing network traffic?

The correct choice, a firewall, is a type of security system designed specifically to monitor and control incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet. Firewalls determine whether to allow or block traffic by analyzing data packets and enforcing policies that protect the network from unauthorized access and potential threats.

In addition to basic packet filtering, firewalls can also offer features such as stateful inspection, where they track the state of active connections and make decisions based on the context of traffic. This functionality is crucial for maintaining network security by preventing attacks and unauthorized access while allowing legitimate communications to occur.

Other options such as servers, clients, and ports serve different roles within a network. Servers provide resources and services to clients, which are the end-user devices. Ports are endpoints for communication on a device but do not perform monitoring or controlling functions like a firewall does. Hence, the firewall is uniquely positioned as a pivotal component in network security management.