ROM stands for Read-Only Memory, a type of computer memory that stores permanent instructions and cannot be modified after manufacture. It's used to store firmware and boot-up instructions. Option A incorrectly says 'Optical' instead of 'Only,' Option B says 'Read' instead of 'Read-Only,' and Option D incorrectly says 'Rapid' instead of 'Read Only.' The 'Read-Only' characteristic means data is stored permanently and cannot be written to after programming.