A technician notices that there is a second partition on the primary hard drive. This partition is not assigned a drive letter and is not accessible from Windows. Which of the following is the MOST likely explanation for this extra partition?（）

• A、Space reserved by the drive manufacturer for firmware.
• B、Space set aside by Windows for use by the virtual memory swap file.
• C、A potentially dangerous virus has been downloaded onto the system.
• D、A recovery partition put there by the manufacturer.