A learn has been working for two months and has consistently missed planned user stories...

The project manager should first check if the sprint size is appropriate for the iteration duration, meaning that the team can realistically complete the user stories within the timebox. This is a way of applying the agile principle of delivering working software frequently and satisfying the customer. If the sprint size is too large or too small, the project manager should work with the team and the product owner to adjust it accordingly, based on the team’s velocity and capacity. This is also a part of the agile practice of adaptive planning and continuous improvement. The other options are not the best choices, as they do not address the root cause of the issue and may introduce more problems. Changing the iteration duration may disrupt the team’s rhythm and alignment with other teams or stakeholders. Recruiting a highly skilled resource may increase the cost and complexity of the project, and may not guarantee the improvement of the team’s performance. Using a reward system may create a competitive or extrinsic motivation that may undermine the team’s collaboration and intrinsic motivation. References: (Professional in Business Analysis Reference Materials source and documents)

A Guide to the Project Management Body of Knowledge (PMBOK® Guide) – Seventh Edition, Chapter 2: Value Delivery System, Section 2.3.2: Iterative and Incremental Development

Business Analysis for Practitioners: A Practice Guide, Chapter 6: Requirements Life Cycle Management, Section 6.3.1: Prioritization

Agile Practice Guide, Chapter 3: Implementing Agile: Creating an Agile Environment, Section 3.3: Team Composition, Roles, and Responsibilities