Object storage is a data storage architecture that manages data as discrete units called objects. Unlike file or block storage, it is accessed programmatically via HTTP-based RESTful APIs. The Amazon Simple Storage Service (S3) API has become the de facto industry standard for interacting with object storage systems. This API allows applications to create, retrieve, update, and delete objects within containers known as buckets. NetApp's object storage solution, StorageGRID, is a prime example of a system that uses the S3 API for data access.

B. NAS: Network Attached Storage (NAS) provides file-level access using protocols like NFS and SMB/CIFS, not the object-based S3 API.

C. inode: An inode is a data structure used in file systems to store metadata about a file; it is not a storage type or access method.

D. SAN: A Storage Area Network (SAN) provides block-level access to storage devices using protocols like Fibre Channel (FC) and iSCSI.

1. NetApp StorageGRID 11.7 Documentation, "Concepts," section "What StorageGRID is."

This official NetApp document states: "StorageGRID is a software-defined object storage solution that supports industry-standard object APIs, including the Amazon Simple Storage Service (S3) API and the Swift API." This directly links the S3 API to the object storage type.

2. NetApp University, "NetApp Data Storage Fundamentals" (Student Guide), Module 1: Storage Fundamentals, "Object Storage" section.

This courseware explains that object storage is accessed through APIs such as REST. It explicitly identifies the Amazon S3 API as having become the de facto standard for object storage access.

3. Carnegie Mellon University, School of Computer Science, "15-719 Advanced Cloud Computing," Lecture 3: Cloud Storage, Slide 11 "Object Storage: Amazon S3."

This university course material presents Amazon S3 as the canonical example of an object storage system, detailing its use of a REST API for key-value access to objects stored in buckets.