The project manager should review the communication needs of key stakeholders because this is the first step in developing an effective communication management plan. By reviewing the communication needs, the project manager can identify what information is relevant, important, and useful for each stakeholder, and tailor the communication accordingly. The other options are not the best choices because they are either too late or too broad. Confirming that the project information is understood and feedback is received (option B) is a good practice, but it does not address the root cause of the problem, which is the missing information.
Determining communication methods, frequency, and level of detail (option C) is part of the communication management plan, but it should be based on the communication needs analysis. Providing all project information to the stakeholder (option D) may overwhelm the stakeholder with unnecessary or irrelevant information, and may also compromise the confidentiality or security of the project. References: PMBOK Guide, 6th edition, pages 361-362, 366-367. PMP Questions page 427. PMP Practice Exam | Free PMP Practice Questions.