Which of the following accurately defines secondary storage?

Secondary storage refers to non-volatile storage that retains data even when the power is turned off. It is designed for long-term data storage, which aligns with the definition provided by the correct choice. This type of storage includes devices such as hard drives, solid-state drives, and optical disks, which can store large amounts of data permanently, contrasting with primary storage (like RAM), which is volatile and temporary—losing data when the system is powered down.

Other definitions do not accurately reflect the characteristics of secondary storage. Options that describe volatile storage or limit to external devices do not encapsulate the full scope of what secondary storage entails. Likewise, storage that interfaces directly with the CPU would typically fall under primary storage or cache, further distinguishing the definitions. Therefore, the accuracy of the correct choice lies in its comprehensive understanding of the permanence and nature of secondary storage.