Which statement best describes the differences between Cisco SMARTnet and Cisco SMARTnet onsite？（）

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