Mediated connectivity for SAP Ariba Cloud Integration Gateway (CIG) involves using a middleware platform to facilitate communication between SAP Ariba and the backend SAP ERP or S/4HANA system. The two officially supported middleware platforms for this scenario are SAP Process Integration/Process Orchestration (PI/PO) and SAP Integration Suite (formerly SAP Cloud Platform Integration - CPI). When configuring the endpoint in CIG, the URL field must point to the specific inbound endpoint of the chosen middleware system that is set up to receive messages from Ariba.

A. The Cloud Connector is used to establish a secure tunnel from SAP BTP to an on-premise system, but the Ariba endpoint URL points to the CPI tenant, not directly to the Cloud Connector.

C. Providing the URL of the SAP system (ERP or S/4HANA) is characteristic of Direct Connectivity, not Mediated Connectivity, as it bypasses the middleware.

1. SAP Help Portal, SAP Ariba Cloud Integration Gateway: Configuration Guide, Section: "How to configure the connection to the middleware". This document explicitly states, "For mediated connectivity, you must configure the connection to the middleware that you are using. You can use SAP Process Orchestration or SAP Cloud Platform Integration as the middleware." It then shows the specific URL fields for each option.

2. SAP Help Portal, SAP Ariba Cloud Integration Gateway: Administration and configuration for SAP Ariba Cloud Integration Gateway, Section: "Configuring connections to middleware". This guide details the configuration steps and specifies entering the "URL of the SAP Process Orchestration system" or the "URL of the SAP Cloud Platform Integration tenant" depending on the chosen mediation tool.