Which of the following is the MOST cost effective way to add large amounts of storage accessible to all users at a company?

USB drives are direct-attached to a single computer and are not designed for large-scale, shared network access for all users.

Direct Attached Storage (DAS) is connected directly to a single server and while it can be shared via the server, it's not as inherently scalable or network-centric for company-wide access as a NAS.

A Storage Area Network (SAN) provides block-level access and is typically much more complex and expensive to implement and manage than a NAS, making it less 'most cost effective' for general user access.

Network Attached Storage (NAS) devices connect directly to a network and provide file-level data access, making them an efficient and cost-effective way to centralize storage and make it available to all users. NAS is generally simpler to implement and manage than a SAN, offering a good balance of capacity, performance, and cost for general file sharing.