An administrator is adding additional memory into a server that registers 1GB of memory in the OS and notices that the system has 2GB of memory physically installed; however, the server only shows 1GB of memory during POST. Which of the following is the MOST likely reason for this?（）

• A、The OS does not support more than 1GB of memory.
• B、The system memory has different manufacture dates.
• C、Two of the memory sticks are defective.
• D、The server is using memory interleaving.