Exam AB-620 Topic 1 Question 3 Discussion

A custom prompt provides a reusable instruction template that controls how the model performs a specific task. The template can define tone, output structure, formatting, constraints, examples, and fallback behavior.
It can then be added as an agent-level tool, called from a topic, or used within an agent flow. This makes option A the correct mechanism for applying consistent instructions wherever the structured response is generated.
The prompt's model is configured separately in the prompt editor. The builder selects the required enterprise- approved model from the Model field or connects an approved deployment from the Microsoft Foundry model catalog. After that model is selected for the custom prompt, every execution of that prompt uses the selected model, making option E correct.
Publishing does not automatically select an appropriate Foundry model; the model must be explicitly configured. Azure AI Search controls retrieval and grounding, not model selection. Citations provide source traceability but do not limit execution to approved models. Defining instructions independently in individual topics would duplicate configuration and weaken consistency.
Relevant AB-620 study-guide topics are Configure advanced agent responses with custom prompts and Configure custom prompts to use the Foundry model catalog . See Use prompts in Copilot Studio and Use Foundry models for prompts .