The BA needs to perform a root cause analysis to analyze the performance of the application and provide recommendations. A root cause analysis is a technique that involves identifying and addressing the underlying causes of a problem or an issue, rather than the symptoms or the effects. A root cause analysis can help the BA to find out why the solution implemented three months ago has decreased performance as the volume of transactions has increased, and to propose and implement appropriate solutions to improve the performance and prevent the problem from recurring. The other options are not the best actions for the BA to take, as they are more suitable for different purposes, such as measuring the performance, evaluating the alternatives, or reviewing the existing metrics, rather than finding the root cause of the problem. References: Task: Assessing Solution Limitations, CBAP / CCBA Certified Business Analysis Study Guide, 2nd Edition, BABOK Guide