Final answer:
RAID is the correct answer as it stands for Redundant Array of Independent Disks and provides immediate backup by combining multiple hard drives.
Step-by-step explanation:
RAID stands for Redundant Array of Independent Disks, which is a technology that combines multiple hard drives into one system to improve performance and provide immediate backup. With RAID, even if one drive fails, the data can still be accessed from another, ensuring that no data is lost. This is different from the other options: BIOS (Basic Input/Output System) which is firmware for initializing computer hardware during booting, VPN (Virtual Private Network) which secures internet connections, and Firewall which acts as a security barrier against unauthorized access to or from a private network.