Which technology has the ability to share data across an Ethernet network and is used primarily for file sharing and unstructured data?

Fibre Channel is a dedicated, high-speed networking technology used for block-level SAN connectivity, not for file sharing over Ethernet.

A storage area network (SAN) provides block-level storage typically over Fibre Channel or iSCSI and does not natively serve file-level access across a general Ethernet network.

Direct-attached storage (DAS) connects directly to a single host via a local bus such as SAS or SATA and is not shared across a network.

NAS uses standard Ethernet connectivity and file-sharing protocols such as NFS and SMB/CIFS to provide file-level storage access to multiple clients simultaneously across a network. This file-centric, Ethernet-based design makes NAS the correct technology for unstructured data and file sharing use cases described in the question.