An organization provides information to its supply chain partners and customers through an extranet infrastructure. Which of the following should be the GREATEST concern to an IS auditor reviewing the firewall security architecture? 
A、A Secure Sockets Layer (SSL) has been implemented for user authentication and remote administration of the firewall. 
B、Firewall policies are updated on the basis of changing requirements. 
C、Inbound traffic is blocked unless the traffic type and connections have been specifically permitted. 
D、The firewall is placed on top of the commercial operating system with all installation options.