The risk manager should review the feature with the project team to determine the cause and impact of the untestability, and to identify possible solutions or alternatives. The risk manager should also update the risk register and the risk response plan accordingly. This is the best option among the given choices, as it involves the relevant stakeholders and follows the risk management process. Confirming the risk triggers are still valid is not sufficient, as it does not address the problem or its consequences. Asking the architect to develop acceptance criteria is not appropriate, as it may not be feasible or effective to test the feature with new criteria. Escalating the issue to the project board is premature, as it may not be necessary or desirable to involve the senior management without first analyzing the situation and proposing a course of action. References: PMI. (2017). A Guide to the Project Management Body of Knowledge (PMBOK® Guide) – Sixth Edition. Chapter 11: Project Risk Management, pp. 414-415. 5

When a key feature may not be testable due to changes in the environment, the risk manager should review the feature with the project team to understand the issue, assess its impact, and determine the appropriate risk response. This collaborative approach ensures that the team has a clear understanding of the situation and can work together to address the risk.