Explanation:

Account Engagement supports only one active CRM connector at a time. The platform is tightly integrated with Salesforce, and although other CRM connectors existed in the past, Salesforce is now the primary focus. Having a single active connector simplifies sync management, user sync, and field mapping. Attempting to use multiple connectors simultaneously could cause data integrity issues and is not supported. Answer C reflects this limitation and aligns with current platform architecture best practices for reliable data synchronization.