The correct option is The AI that autonomously adjusts routes based on live traffic because the Agent layer represents autonomous goal driven components that perceive context, decide, and act.

This component monitors real time signals, invokes models and tools as needed, and updates routes without requiring a human instruction for each step. It optimizes toward delivery objectives, which is the defining behavior of an agent in the generative AI stack.

The foundation model hosted on Vertex AI for route planning belongs to the model layer, which provides generation and reasoning capabilities, yet it does not independently plan and execute actions to meet goals.

The web portal for drivers on example.com is a user interface in the application or presentation layer and it does not perform autonomous decision making or tool use.

Google Kubernetes Engine with attached GPUs is infrastructure that hosts workloads and accelerates computation, yet it is not an agent because it does not make decisions or act toward goals.

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