Which unit is used for long-term storage of information?

The secondary storage unit is indeed the appropriate answer for the unit used for long-term storage of information. Secondary storage refers to non-volatile storage that retains data even when the computer is turned off, allowing for the preservation of files, applications, and the operating system. Common types of secondary storage include hard drives, solid-state drives, CDs, and external storage devices. This type of storage is essential for maintaining data over extended periods and provides the capacity for larger amounts of information compared to primary storage.

In contrast, registers are small storage locations within the CPU designed for quick data processing and are used to hold temporary data during computations. The arithmetic and logic unit (ALU) is responsible for carrying out arithmetic and logic operations, but it does not store data long-term. The memory unit, often referring to RAM, is used for short-term or temporary storage of data that the CPU is currently processing and is cleared when the power is off. Therefore, the secondary storage unit distinctly fulfills the role of long-term data retention, making it the correct choice among the options provided.