After the project charter is approved, the project manager must define detailed requirements, constraints, and assumptions with stakeholders, but not all stakeholders can meet in the short term. How should the project manager gather the necessary input?

The project manager needs to gather detailed requirements, constraints, and assumptions from all relevant stakeholders. Since a group meeting isn't feasible, individual communication (email, phone, in-person) ensures all necessary input is collected. Holding a meeting with only available stakeholders risks missing critical information from those absent. Escalating to the sponsor isn't a solution for gathering input; it's an escalation of a problem. Developing the plan with only the project team before consulting stakeholders is premature and excludes vital input, leading to potential rework and stakeholder dissatisfaction.