According to the PMBOK Guide, a root cause analysis is a technique used to identify the underlying reasons for the occurrence of a problem or a deviation from the expected performance. It is part of the monitor and control project work process, which involves tracking, reviewing, and reporting the project progress and performance, and implementing corrective or preventive actions as needed. A root cause analysis can help the project manager to understand the causes of the budget shift and to take appropriate actions to address them. It can also help to prevent similar problems from happening again in the future. Adjusting the original budget estimates, negotiating the project changes, or reviewing the activity duration are possible actions that the project manager can take after performing a root cause analysis, but they are not the first step to do when faced with a significant budget shift. References:
PMBOK Guide, 6th edition, pages 121-122, 4.5 Monitor and Control Project Work PMBOK Guide, 6th edition, pages 686-687, Root Cause Analysis PMP Sample Test Questions, question 1, answer D

In the face of unforeseen challenges and communication issues that have led to mistakes and delays, it is crucial for the project manager to engage directly with the team to discuss how project objectives can still be met. This involves open communication to understand the root causes of the issues, re-aligning the team's focus on the project goals, and collaboratively developing a plan to overcome the obstacles. This approach is supported by the PMBOKGuide, which emphasizes the importance of clear communication and stakeholder engagement in project management.
: The answer is corroborated by the principles found in the PMBOKGuide, which outlines the need for effective communication and stakeholder engagement throughout the project lifecycle. Additionally, the Professional in Business Analysis (PMI-PBA) reference materials highlight the significance of addressing challenges through teamwork and collaboration to ensure project success.

This question fits the People domain because it focuses on trust, communication, and team dynamics. PMI's People tasks emphasize supporting team performance, removing impediments, and using leadership behaviors such as listening, communicating, negotiating, and facilitating. Here, the issue is not technical competence; it is a breakdown in how communication is being interpreted. The best response is to improve mutual understanding from both sides. Encouraging the team to respectfully ask questions promotes transparency and helps clarify statements that may otherwise be misunderstood. Helping the expert member feel secure enough to communicate more freely addresses the behavioral root cause without becoming punitive.
Option A is too directive and focuses on suppressing phrasing rather than building better dialogue. Option B relies on authority or reputation instead of repairing trust through direct interaction. Option E is unrealistic because trust is built through behavior and clarity, not by simply reminding people to trust all communication.
PMP-style leadership favors servant leadership, active listening, and coaching that improves how the team interacts. For that reason, C and D are the strongest choices.