A project manager is tracking a project, but a key stakeholder will not accept the project's key performance indicator (KPI) results. Which tool or technique should the project manager use?

If a key stakeholder does not accept KPI results, it indicates a potential disagreement about project performance or even the agreed-upon metrics, which might necessitate a formal change request to revise the KPIs or how they are measured and accepted, making change control tools appropriate.

Expert judgment is a technique for analysis and decision-making, but it alone won't resolve a stakeholder's non-acceptance of results without a formal process for addressing the disagreement.

Autocratic decision making is generally counterproductive in stakeholder management and would likely worsen the situation rather than resolving the non-acceptance of KPIs.

A context diagram is used for depicting system boundaries and interactions, not for resolving stakeholder disputes over project performance metrics.