There are four main Cisco certification levels that you can attain as a certified Cisco professional.What is the highest level of certification that is offered？（）

A. CiscoSMARTNet Onsite includes all of the elements of Cisco SMARTnet with the additionalprovision of onsite technician to perform parts replacement
B. CiscoSMARTnet Onsite is primarily attractive to customers who do not need to replace theirhardware immediately， but would still like an onsite technician to install and replace hardware
C. CiscoSMARTnet Onsite includes certification classes and live network consulting at thecustomer site
D. CiscoSMARTnet Onsite provides network monitoring for small-to-medium sized businesses andprovides onsite technical resources when hardware problems are detecteD

A. unified wireless and wired infrastructure for a single point of control for all WLAN traffic
B. simplified management of central or remotely located access points
C. extension features to wired network services， such as denial of service prevention and ACLs
D. threat defense with a robust wired IDS

A. application-level
B. systems-level
C. policy-level
D. advanced services