Which Cisco solution uses model driven APIs based off YANG models?

The correct choice is indeed the solution that utilizes model-driven APIs based on YANG models, which is Network Services Orchestrator (NSO). NSO is specifically designed to manage and automate network services using a model-driven approach. It leverages YANG data models to define configuration and operational states for various network devices, making it highly adaptable and capable of integrating with different network technologies.

Using YANG as a basis for its APIs allows NSO to provide a consistent and standardized interface for developers, facilitating easier integration with other applications and services. This also means that network resources can be manipulated programmatically in a way that reflects their actual state and structure, significantly improving automation capabilities.

Other solutions mentioned, such as ACI (Application Centric Infrastructure), UCS Manager, and VTS (Virtual Topology System), focus on specific aspects of network management and orchestration but do not primarily operate on model-driven APIs based on YANG. While ACI does incorporate some aspects of programmability and automation, it does not utilize YANG models in the same way that NSO does. UCS Manager provides management for Cisco Unified Computing System resources but does not employ model-driven APIs based on YANG, and VTS is more about network virtualization rather than utilizing a YANG