Refer to the exhibit. A network administrator configures a new router and enters the copy startup-config running-config on the router. The network administrator powers down the router and sets it up at a remote location. When the router starts, it enter the system configuration dialog as shown. What is the caust of the problem?（）

• A、The network administrator faled to save the configuration.
• B、The configuration register is set to 0x2100.
• C、The boot system flash command is missing from the configuration.
• D、The configuraiton register is set to 0x2102.
• E、The router is configured with the boot system startup command.