This question belongs to the Process domain because it deals with estimating methods and use of historical information. PMI's current Lexicon defines analogous estimating as estimating duration, cost, or resources using historical data from a similar activity or project. PMI also notes that organizational process assets and lessons-learned repositories can include historical information from previous similar projects that helps support estimating.
Because the activity was performed previously in another company project, the best next step is to consult artifacts from that earlier project . Those records provide the closest available benchmark and allow the team to estimate based on real prior performance rather than guesswork. Option A is weaker because it relies only on opinion when better evidence exists. Option C is incorrect because deadline-driven reverse estimating is unreliable and can create unrealistic commitments. Option D is also inappropriate because the issue is estimation, not resourcing the work with a different team. PMP-style logic favors using historical data first when a comparable reference is available, making analogous estimating the strongest and most defensible approach.

In the context of Project Management Professional (PMP) practices, when a key function is anticipated to take longer to complete, the project manager should engage with the project team to review options and possible solutions. This approach aligns with the principles of iterative planning and agile methodologies, which emphasize collaboration, team engagement, and adaptive planning to address changes and challenges that arise during project execution. It is essential to work with the team to understand the issue's impact on the project's schedule and scope and to explore all possible avenues to mitigate delays while maintaining quality and meeting project objectives.
The answer is verified by the principles found in the PMI's guide to the Project Management Body of Knowledge (PMBOK Guide) and the Disciplined Agile (DA) toolkit, which advocate for a collaborative approach to problem-solving within the team and adapting plans as necessary based on the team's velocity and iteration goals12.

According to the PMBOK Guide, 7th edition, section 5.3.1, "The project scope statement is a component of the project management plan that describes, in detail, the project's deliverables and the work required to create those deliverables. It provides a common understanding of the project scope among project stakeholders and describes the project's major deliverables, assumptions, and constraints." Therefore, the project manager should meet with management to explain the potential problems with running a project without a project scope statement, such as scope creep, misalignment of expectations, poor quality, increased risks, and wasted resources. Escalating the issue to the project sponsor and adding it to the risk register (option A) may be done after meeting with management, but not before. Refusing to work on the project because management is not following standard project management practices (option B) is unprofessional and may damage the relationship with the management and the project stakeholders. Starting the project with inputs from the project charter to save time (option D) may not be feasible or effective, as the project charter is a high-level document that does not provide enough details to define and control the project scope. References:
* PMBOK Guide, 7th edition, section 5.3.1
* PMI-PBA Exam Practice Test and Study Guide, 2nd edition, page 182, question 18

The best course of action for a project manager who is experienced in both predictive and adaptive approaches, when dealing with stakeholders familiar mostly with predictive projects, is to first understand the scope complexity and project magnitude. This initial step is crucial as it helps in determining the most suitable approach for the project at hand. A hybrid approach may be beneficial in some cases, but without a clear understanding of the project's demands and challenges, it's premature to decide on the methodology. The project manager should assess the project's needs, evaluate the stakeholders' familiarity with different methodologies, and consider the potential need for training if an adaptive approach is chosen. This approach aligns with the PMI's guidance on tailoring the project management approach to the unique aspects of the project and the environment in which it operates.
: (Based on the PMI's principles of tailoring the project management approach to the project's characteristics and the stakeholders' expertise.)