Context-Based Access Control (CBAC) is the algorithm of the Cisco IOS firewall feature. How does CBAC improve Teleworker security?（）

• A、Inbound packets are permitted only if they are part of a legitimate data flow initiated by a device on the Teleworker home network.
• B、All packets are checked for integrity by analyzing their checksum.
• C、Every packet is checked to see if it was sent through the VPN tunnel.
• D、Every packet is inspected to see if any disallowed URLs are included. URLs are forwarded to the security cache engine for authorization.