The best course of action to take when the customer reports defects after implementation of the product is to compare reported defects with user acceptance test results. User acceptance testing (UAT) is a process of verifying that the solution meets the requirements and expectations of the end users and delivers value to them. User acceptance testing involves preparing test cases, scenarios, or scripts based on the acceptance criteria, executing them with representative users or stakeholders, collecting feedback, identifying defects or issues, and obtaining sign-off or approval for deployment. By comparing reported defects with user acceptance test results, the business analyst can determine whether the defects were already detected and resolved during UAT, whether they were missed or overlooked during UAT, or whether they emerged after UAT due to changes in the environment, configuration, data, or usage. This can help to assess the impact and severity of the defects and decide on the appropriate actions to address them. Escalating the issue to the project manager since the acceptance was given by the customer is not helpful, as it does not involve investigating or resolving the defects. Doing nothing since the solution is now the responsibility of the operations manager is not responsible, as it does not ensure customer satisfaction or solution quality. Involving the end users and planning a new round of acceptance tests to check the gaps is not feasible, as it may be costly, time-consuming, and disruptive to conduct another UAT after implementation. References: PMI Professional in Business Analysis (PMI-PBA)Examination Content Outline1, page 14; Business Analysis for Practitioners: A Practice Guide2, page 80.