The best way to measure the effectiveness of the subsidiary’s IT systems controls is to review metrics and key performance indicators (KPIs), as they provide quantitative and qualitative measures of the performance and outcomes of the IT systems and processes, and how well they meet the predefined standards and expectations. Metrics and KPIs can help to evaluate the efficiency, reliability, security, and quality of the IT systems and controls, and to identify any gaps, weaknesses, or issues that need to be addressed. Metrics and KPIs can also help to compare and benchmark the subsidiary’s IT systems and controls with those of the parent organization or other similar entities. The other options are not the best ways to measure the effectiveness of the subsidiary’s IT systems controls, although they may be useful or complementary methods. Implementing IT systems in alignment with business objectives is a good practice, but it does not measure the effectiveness of the IT systems controls, as it focuses on the alignment andintegration of the IT systems with the business strategy and goals. Reviewing design documentation of IT systems can provide some information on the specifications and requirements of the IT systems, but it does not measure the effectiveness of the IT systems controls, as it does not reflect the actual implementation and operation of the IT systems. Evaluating compliance with legal and regulatory requirements can ensure that the subsidiary’s IT systems and controls meet the minimum standards and obligations of the foreign country, but it does not measure the effectiveness of the IT systems controls, as it does not consider the performance and outcomes of the IT systems and processes. References = Risk and Information Systems Control Study Manual, Chapter 5: Risk and Control Monitoring and Reporting, page 187.