A retail customer installs a BladeCenter into an existing 10/100 Ethernet network. Due to cost considerations, the customer uses Copper Pass-thru Modules. After installing this solution, the customer finds that they have no network connectivity. Which of the following at is causing the problem?（）

• A、Copper Pass-thru Modules only support 1000Mb line speeds. 
• B、Spanning Tree has been enabled on the Copper Pass-thru Module. 
• C、The customer does not have the latest firmware loaded on the Copper Pass-thru Module. 
• D、The customer is using LS21 Blades