Which of the following is used in Object-Based Storage to reference the servers that provide services to store, retrieve, and manage data in the Object-Based Storage system?

A controller in storage contexts typically refers to a hardware or software component that manages a SAN or RAID array, not servers in an object storage system.

A host is the client machine that accesses the storage system to read or write data, not a server within the object storage infrastructure itself.

In object-based storage architectures such as Ceph or Swift, a node is a physical or virtual server that participates in the storage cluster to handle data storage, retrieval, and management operations. Nodes can serve roles such as object storage daemons or data servers depending on the implementation. The term node is the standard terminology used to describe these peer servers within a distributed object storage system.

A switch is a network device used to interconnect components and does not provide storage, retrieval, or data management services.