In the final iteration of a hybrid project, a key team member wants to leave. How should the project manager respond?

The correct answer is to have a meeting with the resource to understand the issue. Before taking any action, the project manager needs to understand the reasons behind the team member's desire to leave. This allows for potential resolution, negotiation, or a smoother transition. Updating the burndown chart is a reactive measure that doesn't address the root cause. Keeping activities unchanged is unrealistic and irresponsible, as a key resource's departure will undoubtedly impact the project. Requesting an additional resource might be a necessary step, but it should only be considered after understanding the situation with the current team member and exploring all other options.