Explanation
According to the PMBOK Guide 7th Edition, the project charter is a document that authorizes the project and defines its high-level scope, objectives, assumptions, constraints, and key stakeholders. The project charter should be approved by the project sponsor and communicated to all relevant stakeholders, including senior managers, to ensure their alignment and commitment to the project. If some of the senior managers claim not to know about the deliverable, it indicates that they may not have been properly informed or involved in the project charter development or approval process. Therefore, the project manager should meet with these stakeholders to review the project charter and clarify their roles, responsibilities, expectations, and interests in the project. This will help to resolve any confusion or conflict and to gain their support and buy-in for the project. Checking if these stakeholders attend regular project meetings, reviewing the project charter, or validating if the project charter changed are not sufficient actions, as they do not address the root cause of the communication gap or the stakeholder engagement issue, and they may not improve the relationship or trust between the project manager and the senior managers. References: PMBOK Guide 7th Edition, page 45-46.