Functional specifications are a type of requirements documentation that describes what the system or product should do in terms of functions, features, behaviors, inputs, outputs, etc. Functional specifications can help the business analyst to document the requirements in a way that is clearly understood by the development team and provides enough information to check if the requirement has been met. Functional specifications can also include acceptance criteria, test cases, data models, user interface designs, etc. References: = PMI Professional in Business Analysis (PMI-PBA)Examination Content Outline (2019), page 10; Business Analysis for Practitioners: A Practice Guide (2015), page 39.

Root cause analysis is a technique that involves identifying and analyzing the underlying causes of a problem or an issue. Root cause analysis can help the business analyst to determine how the selection criteria requirement was missed, and to prevent similar errors from occurring in the future. Root cause analysis can be done using various tools, such as fishbone diagram and the Five Whys. A fishbone diagram is a graphical tool that organizes the possible causes of a problem into categories, such as people, process, technology, environment, etc. A fishbone diagram can help the business analyst to visualize the relationships between the causes and the effects, and to identify the most likely root causes. The Five Whys is a questioning technique that involves asking "why" repeatedly until the root cause of a problem is revealed. The Five Whys can help the business analyst to drill down into the details of the problem, and to uncover the underlying factors and assumptions that led to the missed requirement. References: PMI Professional in Business Analysis (PMI- PBA) Examination Content Outline1, page 21; Business Analysis for Practitioners: A Practice Guide2, page
101.

Explanation
The business analyst should check the traceability matrix to identify affected use cases. A traceability matrix can help the business analyst to find out which use cases are related to the new set of regulations, and how they will impact the scope, schedule, cost, quality, and risk of the project. The business analyst should also communicate the changes to the relevant stakeholders, and update the requirements documentation and the business analysis plan accordingly. : PMI Professional in Business Analysis (PMI-PBA) Examination Content Outline1, page 20; Business Analysis for Practitioners: A Practice Guide2, page 100.