Which of the following memory technologies has the HIGHEST cost to implement?

The correct choice is based on the fact that RAID (Redundant Array of Independent Disks) involves not just the cost of memory or individual hard drives, but also includes additional costs associated with hardware and software configurations, controllers, and potentially server upgrades to support the RAID setup. Implementing a RAID solution often requires specialized hardware, such as RAID controllers, which can significantly increase the overall expense. In addition, the need for redundancy usually means that more disks or higher-capacity disks must be deployed compared to simple storage configurations, leading to increased costs.

In contrast, memory types like ECC (Error-Correcting Code) and Registered memory may have higher per-unit costs than standard memory, but these costs typically do not match the total investment associated with a robust RAID implementation. Pairing, which refers to techniques like using matched pairs in memory configurations, is more about optimizing performance rather than a straight investment in technology. Therefore, RAID is the highest cost option when considering the complete scope of the implementation.