Within the context of SAP Business Data Cloud (BDC), the primary and most central source system for an SAP Analytics Cloud (SAC) live connection is SAP Datasphere. SAP Datasphere serves as the comprehensive data foundation for SAP's business data fabric, integrating data from various SAP and non-SAP sources, and providing a harmonized, semantically rich data layer. SAP BDC is built upon and extends the capabilities of SAP Datasphere, making it the strategic hub for analytics and data management. Therefore, to ensure data consistency, governance, and real-time access to the integrated and harmonized business data managed within the BDC ecosystem, SAP Datasphere is the recommended and primary live connection source for SAC. While SAC can connect to other SAP systems like S/4HANA or BW, within the specific architecture of SAP BDC, SAP Datasphere plays the pivotal role as the integrated data platform.

The remote table feature in SAP Datasphere offers significant flexibility in how data from external sources is consumed and managed. Firstly, data can be accessed virtually by remote access to the source system (E). This means Datasphere does not store a copy of the data; instead, it queries the source system in real-time when the data is requested. This ensures that users always work with the freshest data. Secondly, data can be persisted in SAP Datasphere by creating a snapshot (copy of data) (C). This allows users to explicitly load a copy of the remote table's data into Datasphere at a specific point in time, useful for performance or offline analysis. Lastly, data can be persisted by using real-time replication (D). For certain source systems and configurations, Datasphere supports continuous, real-time replication, ensuring that changes in the source system are immediately reflected in the persisted copy within Datasphere. Option A is incorrect as the access mode cannot be arbitrarily switched, and option B refers to data flow capabilities, not inherent remote table access options.