The agile leader should speak directly with the team member about improvements and commit to an agreed-upon time frame. This is the best option because it shows the agile leader's respect and empathy for the team member, as well as the willingness to help them overcome their challenges and grow their skills. By speaking directly with the team member, the agile leader can also understand the root cause of the problem, provide constructive feedback, and agree on a realistic and achievable plan for improvement. This option also aligns with the agile values of "individuals and interactions over processes and tools" and "responding to change over following a plan"1.
The other options are not as effective as option D. Option A is not supportive and may demotivate the team member and create resentment. Option B is not appropriate and may embarrass the team member and lower the team morale. Option C is not relevant and may not address the team member's specific needs and gaps. References: 1: Agile Manifesto, [Manifesto for Agile Software Development]

According to the Project Management Body of Knowledge (PMBOK), a project manager's role includes managing and leading the project team, which involves addressing team members' concerns and issues. In this scenario, the project manager should empathize with the team member and discuss next steps. This approach ensures that the team member feels heard and supported, and it can help to alleviate their stress and anxiety about the upcoming deadline. References: PMBOK Guide, 6th Edition, Section 9: Project Resource Management.

When a team member leaves a project, it can introduce risks and uncertainties. The first step for the project manager should be to review the risk management plan and any mitigation plans that are in place. This will help the project manager understand the potential impact of the team member's departure on the project and determine the best course of action. The project manager can then decide whether to ask the functional manager for a replacement, or if other strategies should be employed to ensure the project stays on track12. References: Online PM Courses, Brainscape

The best answer is D because it involves engaging the stakeholders in the decision-making process and respecting their preferences and expectations. The project manager should not impose a new approach on the stakeholders without their consent or input, as this could lead to resistance, confusion, or dissatisfaction. The project manager should also not delegate the decision to the team only, as this could exclude the stakeholders' perspectives and needs. The project manager should explain the benefits and challenges of both the predictive and agile approaches, and facilitate a collaborative discussion with the stakeholders to reach a mutual agreement on the best approach for the new project. This would demonstrate the project manager's leadership, communication, and stakeholder management skills, as well as the ability to adapt to changing organizational and environmental factors. References:
* PMBOK Guide, 7th edition, page 27, section 2.2.1, "Tailoring"
* PMBOK Guide, 7th edition, page 29, section 2.2.2, "Stakeholder Engagement"
* PMBOK Guide, 7th edition, page 31, section 2.2.3, "Leadership"
* PMBOK Guide, 7th edition, page 33, section 2.2.4, "Teamwork"
* PMBOK Guide, 7th edition, page 35, section 2.2.5, "Communication"
* Agile Practice Guide, page 8, section 1.2, "What is Agile?"
* Agile Practice Guide, page 9, section 1.3, "Why Use Agile Approaches?"
* Agile Practice Guide, page 10, section 1.4, "When to Use Agile Approaches?"
* Agile Practice Guide, page 11, section 1.5, "Tailoring to the Project Environment"
* Agile Practice Guide, page 12, section 1.6, "Implementing Agile: Creating an Agile Environment"
* Agile Practice Guide, page 13, section 1.7, "Implementing Agile: Delivering in an Agile Environment"
* Agile Practice Guide, page 14, section 1.8, "Organizational Considerations for Project Agility"