B and C provide the strongest architecture for reusable and predictable prompts. Separating persistent application instructions from dynamic user input establishes a clear instruction hierarchy . The stable portion of the prompt can define application behavior while channel-specific or request-specific content remains variable. This reduces coupling between user wording and the behavioral rules of the assistant and makes the prompt easier to reuse, version, test, and modify.

The system prompt should establish the model ' s role, behavioral boundaries, tone, communication style, response format, and other persistent rules. Microsoft specifically describes system messages as high-priority instructions used to define an assistant ' s role and boundaries and to set tone and communication style.

Fine-tuning for every conversational variation is unnecessarily expensive and contradicts the requirement to remain adaptable without retraining. Increasing temperature increases randomness and therefore works against consistent responses. Although repeating important instructions can sometimes mitigate recency effects, Microsoft treats this as an optional prompt-engineering technique to experiment with, not the primary architectural technique for producing reusable prompts.

Study Guide Reference: Design and implement a GenAIOps infrastructure — design and develop prompts, prompt management, prompt variants, system instructions, and reusable prompt structures.

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