According to the PMBOKGuide, 7th edition, one of the principles of project management is to collaborate with stakeholders and team members1. This principle emphasizes the importance of establishing and maintaining a shared understanding of the project vision, objectives, and expectations among all project participants. It also suggests that project managers should foster a team culture that supports collaboration, trust, learning, and adaptation1.
In an agile project, the team rules are a set of agreements that define how the team will work together, communicate, and deliver value2. The team rules should be established at the beginning of the project and reviewed periodically to ensure they are still relevant and effective2. The team rules should also be aligned with the agile values and principles, such as responding to change over following a plan and individuals and interactions over processes and tools3.
In this scenario, the project manager observes that the team is having problems meeting their goals in the second iteration. This could indicate that the team rules are not clear, not followed, or not suitable for the current situation. Therefore, the best course of action for the project manager is to provide feedback to the team and conduct a meeting to review the team rules. This will help the team to identify and resolve any issues or conflicts that are affecting their performance, and to update or modify the team rules as needed. This will also help the new team member who does not have agile experience to understand and adapt to the team's way of working.
The other options are not as effective as option A. Option B, conducting a retrospective meeting to find a root cause, is a good practice for agile teams, but it is usually done at the end of each iteration, not in the middle. A retrospective meeting is also focused on evaluating the past iteration and identifying improvement actions for the next one, not on reviewing the team rules. Option C, requesting agile training for the new member, may be helpful, but it does not address the immediate problem of the team's performance. It also assumes that the new member is the only source of the problem, which may not be true. Option D, coaching the new team member in agile methodology, is also a good practice, but it is not the primary responsibility of the project manager.
The project manager should delegate the coaching task to a more experienced team member or a mentor, and focus on facilitating the team's collaboration and alignment.
References: 1: PMBOKGuide, 7th edition, page 9 2: PMBOKGuide, 7th edition, page 95 3: Agile Manifesto, 4

Section: Monitoring and Controlling