During project execution, the project manager discovered that a key deliverable was missing from the...

The project manager should submit a change request to update the scope of work, the schedule, and the budget to accommodate the missing deliverable. A change request is a formal proposal to modify any aspect of the project, such as the scope, schedule, cost, quality, resources, or risks. A change request must be documented, reviewed, approved, and communicated by following the change control process. The change control process is part of the perform integrated change control process, which is one of the processes in the project integration management knowledge area. By submitting a change request, the project manager can ensure that the missing deliverable is properly identified, analyzed, and integrated into the project plan, and that the impact on the project objectives and constraints is minimized. The other options are not correct. Adding additional resources to the project may not solve the problem of the missing deliverable, and it may also introduce new risks, costs, and communication issues. Updating the scope of work without submitting a change request may lead to scope creep, which is the uncontrolled expansion of the project scope without proper authorization and approval. Reviewing the risk management plan may help to identify and mitigate any potential risks related to the missing deliverable, but it does not address the root cause of the problem or the impact on the project plan. References: PMBOK Guide, 6th edition, Chapter 4.6, 5.6, How to Manage Change Requests on a Project - PMI