单选题 Basically，a firewall if a ______ process or a set of integrated processes that runs on a router or______ to control the flow of networked application traffic!______ through it．Typically，firewallsare placed on the entry point to a ______ network such as the Internet．They could be consideredtraffic cops．The firewall"s ______ is to ensure that all communication between an organization"snetwork and the intemet conform to the organization"s security policies．