A vendor informed the project manager that a critical resource will be on a long leave of absence. The project team reviewed the pending vendor deliverables and identified an alternative solution, but the solution will incur an additional cost. The project is currently an schedule and slightly under budget. What should the project manager do next?

While conducting a cost-benefit analysis can be useful, it is not the immediate next step in this scenario. The project already has an identified alternative solution; thus, the focus should be on managing the change rather than analyzing costs that have already changed due to the vendor's absence.

Implementing risk responses is applicable when addressing known risks. In this case, the critical resource's absence has led to a change in the project’s deliverables, requiring formal processing through Integrated Change Control rather than just executing risk responses without proper evaluation.

Requesting a replacement resource may seem like a direct solution, but it does not address the immediate need to assess the implications of the additional costs on the project. This action could be part of the change control process, but it does not encompass the necessary evaluation and approval steps required to maintain project integrity.