Prompt-grounding means ensuring Copilot's response is based on authoritative, relevant source material rather than inferred or generalized information. Microsoft guidance for Copilot emphasizes that the most effective way to ground responses is to explicitly point Copilot to the content you want it to use---such as specific SharePoint documents, OneDrive files, emails, meeting notes, or other Microsoft 365 resources the user has permission to access.

Option D is therefore the best answer because referencing specific files anchors Copilot's reasoning to the exact material that should be used for facts, terminology, and details. This reduces hallucinations (fabrication) and improves accuracy and traceability, especially when Copilot can provide citations back to the referenced sources.

Option B (desired output format) improves structure and readability but does not, by itself, ground content. Option A can sometimes improve clarity, but shorter prompts do not guarantee grounding. Option C may help comprehension in some cases, but it is not a grounding strategy and can be counterproductive if the source material is technical.

Therefore, the best approach to improve prompt-grounding is to reference specific files.