When data must reside on-premises due to security or compliance policies, but needs to be visible and actionable in Salesforce, the architect should recommend Data Virtualization via Salesforce Connect.

Salesforce Connect allows Salesforce to treat external data as if it were stored natively in the org without ever moving the data into the Salesforce cloud.28 This is achieved by creating External Objects that map to the on-premises data structures. For this to work seamlessly, the on-premises system or a middleware layer must expose the data through a compatible protocol, most commonly the Open Data Protocol (OData).

Option C is incorrect because Salesforce Connect does not natively support ODBC directly; ODBC is a low-level driver protocol, whereas OData is a web-based RESTful protocol designed for cross-platform data exchange. Option B is irrelevant as the data is stated to be on-premises, not in Heroku. By using Salesforce Connect with OData, the architect satisfies the 'stay on-premises' policy while providing Salesforce users with real-time, bidirectional access to the data, supporting features like Global Search and related lists without the overhead of data synchronization.