During execution a team member is unable to complete their work on time and is behind schedule, potentially affecting a milestone. What should the project manager do first?

The project manager's first step should be to discuss the situation with the team and assess the reasons for the delay. This allows for a direct understanding of the root cause, which is crucial for developing an effective solution. Without understanding why the delay occurred, any proposed solution might be ineffective or even detrimental. Discussing with senior management (option A) is premature; the PM should first gather facts. Asking the team member's manager (option C) delegates the PM's responsibility and might not yield a complete picture. Assigning additional resources (option D) is a potential solution, but it's premature before understanding the problem's nature and might not address the underlying issue, potentially just shifting the problem.